Add link to parcel-transformer-mdx in docs

Closes GH-2523.

Co-authored-by: South Drifted <[email protected]>

Author: wooorm

docs/docs/getting-started.mdx

@@ -621,6 +621,12 @@ See [Configuring MDX on `nextjs.org`][next-configuring-mdx] for more info.
 See [`@parcel/transformer-mdx`][parcel-mdx]
 on how to use MDX with Parcel.
 
+<Note type="info">
+  **Note**: the official Parcel plugin is currently not maintained.
+  For a maintained alternative,
+  try [`parcel-transformer-mdx`][parcel-transformer-mdx].
+</Note>
+
 ### JSX runtimes
 
 #### Emotion
@@ -879,6 +885,8 @@ MDX files can be imported in [Bun][] by using
 
 [parcel-mdx]: https://parceljs.org/languages/mdx/
 
+[parcel-transformer-mdx]: https://github.com/EasyWebApp/Parcel-transformer-MDX
+
 [rollup]: https://rollupjs.org
 
 [svelte-jsx]: https://github.com/kenoxa/svelte-jsx