Added migration page overview

pages/specification/migration/_index.md

@@ -5,76 +5,76 @@ section: docs
 
 ### Introduction
 
-Migrations are like version control for your system, allowing your team to define and share the schema progressions. If you have ever had to figure out when a keyword was introduced and how it behaved, you've faced the problem that migration guides solve.
+Just as your schemas evolve over time, the JSON Schema specification does as well. This guide provides useful information to make upgrading your schemas across versions of the specification a breeze.
 
-If you're moving from one Draft to another, learn how to use our migration guides and tooling ([AlterSchema](https://alterschema.sourcemeta.com/)) to bring your work with you.
+Learn how to use our migration guides and tooling ([AlterSchema](https://alterschema.sourcemeta.com/)) to bring your work with you.
 
 ### Keywords Overview
 
 Here is a comprehensive overview to get you going.
 
-| All Keywords          | Specification          | Draft introduction | Removed | Changed                       |
-| --------------------- | ---------------------- | ------------------ | ------- | ----------------------------- |
-| $anchor               | Core                   | 2019-09            | No      | No (updated in 2020)          |
-| `$comment`              | Core                   | 07                 | Yes     | -                             |
-| $id                   | Core                   | 06                 | No      | Updated from id               |
-| $defs                 | Core                   | 2019-09            | No      | Updated from definitions      |
-| $dynamicAnchor        | Core                   | 2020-12            | No      | Updated from $recursiveAnchor |
-| $dynamicRef           | Core                   | 2020-12            | No      | Updated from $recursiveRef    |
-| $recursiveAnchor      | Core                   | 2019-09            | No      | Updated to $dynamicAnchor     |
-| $recursiveRef         | Core                   | 2019-09            | No      | Updated to $dynamicRef        |
-| $ref                  | Core                   | 2019-09            | No      | No                            |
-| $schema               | Core                   | 02                 | No      | No                            |
-| $vocabualry           | Core                   | 2019-09            | No      | No                            |
-| additionalItems       | Validation             | 03                 | No      | No                            |
-| allOf                 | Validation             | 04                 | No      | No                            |
-| anyOf                 | Validation             | 04                 | No      | No                            |
-| const                 | Validation             | 06                 | No      | No                            |
-| contains              | Validation             | 06                 | No      | No                            |
-| contentEncoding       | Validation             | 07                 | No      | No                            |
-| contentMediaType      | Validation             | 07                 | No      | No                            |
-| contentSchema         | Content                | 2019-09            | No      | No                            |
-| definitions           | Validation             | 04                 | No      | Updated to $defs              |
-| default               | Annotation             | 01                 | No      | No                            |
-| dependencies          | Core                   | 03                 | No      | No                            |
-| dependentRequired     | Validation             | 2019-09            | No      | No                            |
-| dependentSchemas      | Applicator             | 2019-09            | No      | Updated from dependencies     |
-| deprecated            | Annotation             | 2019-09            | No      | No                            |
-| disallow              | Validation             | 03                 | Yes     | No                            |
-| divisibleBy           | Validation             | 02                 | No      | Updated to multipleOf         |
-| else                  | Validation             | 07                 | No      | No                            |
-| enum                  | Assertion              | 01                 | No      | No                            |
-| examples              | Validation             | 06                 | No      | No                            |
-| exclusiveMaximum      | Validation             | 03                 | No      | Updated from maximumCanEqual  |
-| exclusiveMinimum      | Validation             | 03                 | No      | Updated from minimumCanEqual  |
-| extends               | Validation             | 03                 | Yes     | No                            |
-| format                | Annotation             | 02                 | No      | -                             |
-| id                    | Core                   | 04                 | No      | Updated to $id                |
-| if                    | Validation             | 07                 | No      | No                            |
-| items                 | Applicator             | 2019-09            | No      | Updated to prefixItems        |
-| maxContains           | Validation             | 2019-09            | No      | No                            |
-| maxProperties         | Validation             | 04                 | No      | No                            |
-| maximumCanEqual       | Validation             | 02                 | No      | Updated to exclusiveMaximum   |
-| minimumCanEqual       | Validation             | 02                 | No      | Updated to exclusiveMinimum   |
-| minContains           | Validation             | 2019-09            | No      | No                            |
-| minProperties         | Validation             | 04                 | No      | No                            |
-| multipleOf            | Validation             | 04                 | No      | Updated from divisibleBy      |
-| not                   | Validation             | 04                 | No      | No                            |
-| oneOf                 | Validation             | 04                 | No      | No                            |
-| optional              | Validation             | 02                 | No      | Updated to (required)         |
-| pattern               | Core                   | 03                 | No      | No                            |
-| patternProperties     | Validation             | 03                 | No      | No                            |
-| prefixItems           | Applicator             | 2020-12            | No      | Updated from items            |
-| propertyNames         | Validation             | 06                 | No      | No                            |
-| readOnly              | Validation             | 07                 | No      | No                            |
-| required              | Validation             | 03                 | No      | No                            |
-| requires              | Validation             | 02                 | Yes     | -                             |
-| title                 | Annotation             | 01                 | No      | No                            |
-| then                  | Validation             | 07                 | No      | No                            |
-| type                  | Validation             | 02                 | No      | No                            |
-| unevaluatedItems      | Applicator, Annotation | 2019-09            | No      | No                            |
-| unevaluatedProperties | Applicator, Annotation | 2019-09            | No      | No                            |
-| uniqueItems           | Assertion              | 02                 | Yes     | No                            |
-| writeOnly             | Validation             | 07                 | No      | No                            |
+| All Keywords            | Specification | Draft introduction | Removed | Changed                        |
+| ----------------------- | ------------- | ------------------ | ------- | ------------------------------ |
+| `$anchor`               | Core          | 2019-09            | No      | No (updated in 2020)           |
+| `$comment`              | Core          | 07                 | Yes     | -                              |
+| `$id`                   | Core          | 06                 | No      | Replaced `id`                  |
+| `$defs`                 | Core          | 2019-09            | No      | Replaced `definitions`         |
+| `$dynamicAnchor`        | Core          | 2020-12            | No      | Replaced `$recursiveAnchor`    |
+| `$dynamicRef`           | Core          | 2020-12            | No      | Replaced `$recursiveRef`       |
+| `$recursiveAnchor`      | Core          | 2019-09            | No      | Replaced by `$dynamicAnchor`   |
+| `$recursiveRef`         | Core          | 2019-09            | No      | Replaced by `$dynamicRef`      |
+| `$ref`                  | Core          | 2019-09            | No      | No                             |
+| `$schema`               | Core          | 02                 | No      | No                             |
+| `$vocabualry`           | Core          | 2019-09            | No      | No                             |
+| `additionalItems`       | Core          | 03                 | No      | No                             |
+| `allOf`                 | Core          | 04                 | No      | No                             |
+| `anyOf`                 | Core          | 04                 | No      | No                             |
+| `const`                 | Validation    | 06                 | No      | No                             |
+| `contains`              | Core          | 06                 | No      | No                             |
+| `contentEncoding`       | Validation    | 07                 | No      | No                             |
+| `contentMediaType`      | Validation    | 07                 | No      | No                             |
+| `contentSchema`         | Validation    | 2019-09            | No      | No                             |
+| `definitions`           | Validation    | 04                 | No      | Replaced by` $defs`            |
+| `default`               | Validation    | 01                 | No      | No                             |
+| `dependencies`          | Core          | 03                 | No      | No                             |
+| `dependentRequired`     | Validation    | 2019-09            | No      | No                             |
+| `dependentSchemas`      | Core          | 2019-09            | No      | Replaced `dependencies`        |
+| `deprecated`            | Validation    | 2019-09            | No      | No                             |
+| `disallow`              | Validation    | 03                 | Yes     | No                             |
+| `divisibleBy`           | Validation    | 02                 | No      | Replaced by `multipleOf`       |
+| `else`                  | Core          | 07                 | No      | No                             |
+| `enum`                  | Validation    | 01                 | No      | No                             |
+| `examples`              | Validation    | 06                 | No      | No                             |
+| `exclusiveMaximum`      | Validation    | 03                 | No      | Replaced `maximumCanEqual`     |
+| `exclusiveMinimum`      | Validation    | 03                 | No      | Replaced `minimumCanEqual`     |
+| `extends`               | Validation    | 03                 | Yes     | No                             |
+| `format`                | Validation    | 02                 | No      | -                              |
+| `id`                    | Core          | 04                 | No      | Replaced by `$id`              |
+| `if`                    | Core          | 07                 | No      | No                             |
+| `items`                 | Core          | 2019-09            | No      | Replaced by `prefixItems`      |
+| `maxContains`           | Validation    | 2019-09            | No      | No                             |
+| `maxProperties`         | Validation    | 04                 | No      | No                             |
+| `maximumCanEqual`       | Validation    | 02                 | No      | Replaced by `exclusiveMaximum` |
+| `minimumCanEqual`       | Validation    | 02                 | No      | Replaced by `exclusiveMinimum` |
+| `minContains`           | Validation    | 2019-09            | No      | No                             |
+| `minProperties`         | Validation    | 04                 | No      | No                             |
+| `multipleOf`            | Validation    | 04                 | No      | Replaced `divisibleBy`         |
+| `not`                   | Core          | 04                 | No      | No                             |
+| `oneOf`                 | Core          | 04                 | No      | No                             |
+| `optional`              | Validation    | 02                 | No      | Replaced by `required`         |
+| `pattern`               | Core          | 03                 | No      | No                             |
+| `patternProperties`     | Core          | 03                 | No      | No                             |
+| `prefixItems`           | Core          | 2020-12            | No      | Replaced `items`               |
+| `propertyNames`         | Core          | 06                 | No      | No                             |
+| `readOnly`              | Validation    | 07                 | No      | No                             |
+| `required`              | Validation    | 03                 | No      | No                             |
+| `requires`              | Validation    | 02                 | Yes     | -                              |
+| `title`                 | Validation    | 01                 | No      | No                             |
+| `then`                  | Core          | 07                 | No      | No                             |
+| `type`                  | Validation    | 02                 | No      | No                             |
+| `unevaluatedItems`      | Core          | 2019-09            | No      | No                             |
+| `unevaluatedProperties` | Core          | 2019-09            | No      | No                             |
+| `uniqueItems`           | Assertion     | 02                 | Yes     | No                             |
+| `writeOnly`             | Validation    | 07                 | No      | No                             |
 
 For a detailed read-through about all the changes see each Draft migration guide.