docs: fix syntax issue in blocks field (#11855)

<!--

Thank you for the PR! Please go through the checklist below and make
sure you've completed all the steps.

Please review the
[CONTRIBUTING.md](https://github.com/payloadcms/payload/blob/main/CONTRIBUTING.md)
document in this repository if you haven't already.

The following items will ensure that your PR is handled as smoothly as
possible:

- PR Title must follow conventional commits format. For example, `feat:
my new feature`, `fix(plugin-seo): my fix`.
- Minimal description explained as if explained to someone not
immediately familiar with the code.
- Provide before/after screenshots or code diffs if applicable.
- Link any related issues/discussions from GitHub or Discord.
- Add review comments if necessary to explain to the reviewer the logic
behind a change

-->

### What?

This PR fixes the config example in the block field page.

### Why?

The syntax was incorrect

### How?

Missing object property

Author: kristian240

Diff for: docs/fields/blocks.mdx

@@ -359,10 +359,12 @@ const config = buildConfig({
           name: 'editor',
           type: 'richText',
           editor: lexicalEditor({
-            BlocksFeature({
-              // Same reference can be reused anywhere, even in the lexical editor, without incurred performance hit
-              blocks: ['TextBlock'],
-            })
+            features: [
+              BlocksFeature({
+                // Same reference can be reused anywhere, even in the lexical editor, without incurred performance hit
+                blocks: ['TextBlock'],
+              }),
+            ],
           })
         },
       ],