docs(misc): update migration docs to use supported markdown syntax (#33563)

This PR cleans up the markdown files under `packages/`. We previously
had to support Next.js docs and translate it for astro docs with proper
markdown syntax. This applies to generators, executors, and migrations.

Also removes the function to do the translation in astro app since it's
no longer needed.

## Code block (migrations)
<img width="1086" height="800" alt="Screenshot 2025-11-20 at 1 23 53 PM"
src="https://github.com/user-attachments/assets/bd9acb9b-7960-4e41-9d26-22d29da6658e"
/>

## Aside (generators)
<img width="802" height="443" alt="Screenshot 2025-11-20 at 1 43 17 PM"
src="https://github.com/user-attachments/assets/e2999821-8783-46ed-a984-2193f6f8eafa"
/>

Author: jaysoo

astro-docs/src/plugins/utils/generate-plugin-markdown.ts

@@ -7,7 +7,6 @@ import {
   type PluginItem,
   type PluginMigrationItem,
 } from './plugin-schema-parser';
-import { stripMarkdocTags } from './strip-markdoc-tags';
 
 export function generateMigrationItem(name: string, item: any): string {
   const { config } = item;
@@ -34,7 +33,7 @@ export function generateMigrationItem(name: string, item: any): string {
     const maybeExampleMdFile = config.fullPath + '.md';
     if (existsSync(maybeExampleMdFile)) {
       const rawContent = readFileSync(maybeExampleMdFile, 'utf-8');
-      markdown += `${stripMarkdocTags(rawContent)}\n\n`;
+      markdown += `${rawContent}\n\n`;
     }
   }
 

astro-docs/src/plugins/utils/get-schema-example-content.ts

@@ -1,7 +1,7 @@
 import { existsSync, readFileSync } from 'node:fs';
 import { dirname, resolve as resolvePath } from 'node:path';
 import { type PluginSchemaWithExamples } from './plugin-schema-parser';
-import { stripMarkdocTags } from './strip-markdoc-tags';
+
 const EXAMPLE_SCHEMA_KEY = 'examplesFile';
 
 /**
@@ -61,14 +61,11 @@ export function getExampleForSchema(
     return null;
   }
 
-  // Strip Markdoc tags and transform to Starlight syntax
-  const cleanedContent = stripMarkdocTags(content);
-
   // If content already has headers, increase their level by 1 to nest under generator
-  if (hasHeaders(cleanedContent)) {
-    return cleanedContent.replace(/^(#{1,5})\s/gm, '#$1 ');
+  if (hasHeaders(content)) {
+    return content.replace(/^(#{1,5})\s/gm, '#$1 ');
   }
 
   // Only add Examples header if there are no existing headers
-  return `### Examples\n\n${cleanedContent}`;
+  return `### Examples\n\n${content}`;
 }