docs: improvements to create plugin guide (#4285)

* docs: improvements to create plugin guide

* fix link

docs/content/development/entities/create.md

@@ -186,4 +186,4 @@ With entities, you can create relationships, index keys, and more. As Medusa use
 ## See Also
 
 - [Extend Entity](./extend-entity.md)
-- [Create a Plugin](../plugins/create.md)
+- [Create a Plugin](../plugins/create.mdx)

docs/content/development/entities/migrations/create.md

@@ -17,7 +17,7 @@ npx typeorm migration:create src/migrations/UserChanged
 
 This will create the migration file in the path you specify. You can use this without the need to install Typeorm's CLI tool. You can then go ahead and make changes to it as necessary.
 
-The migration file must be inside the `src/migrations` directory. When you run the build command, it will be transpiled into the directory `dist/migrations`. The `migrations run` command can only pick up migrations under the `dist/migrations` directory on a Medusa backend. This applies to migrations created in a Medusa backend, and not in a Medusa plugin. For plugins, check out the [Plugin's Structure section](../../plugins/create.md).
+The migration file must be inside the `src/migrations` directory. When you run the build command, it will be transpiled into the directory `dist/migrations`. The `migrations run` command can only pick up migrations under the `dist/migrations` directory on a Medusa backend. This applies to migrations created in a Medusa backend, and not in a Medusa plugin. For plugins, check out the [Plugin's Structure section](../../plugins/create.mdx).
 
 <details>
   <summary>Generating Migrations for Entities</summary>
@@ -99,4 +99,4 @@ If you check your database now you should see that the change defined by the mig
 
 ## See Also
 
-- [Create a Plugin](../../plugins/create.md)
+- [Create a Plugin](../../plugins/create.mdx)