Update inserting tables in fields.markdoc/fields.mdx to include a table header row by default and remove button to toggle table header in fields.mdx

[emmatown]

Fixes #1283

[changeset-bot]

🦋 Changeset detected

Latest commit: 1a0acfe

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@keystatic/core	Patch
@keystar/docs	Patch
@example/astro-content	Patch
@example/astro	Patch
@example/localization	Patch
@example/next-app	Patch
@example/next-block-builder	Patch
@example/next-pages	Patch
@keystatic/remix-test-app	Patch
keystatic-docs	Patch
@keystatic/templates-astro	Patch
@keystatic/templates-nextjs	Patch
@keystatic/templates-remix	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR