Add recma-mdx-change-props, recma-mdx-escape-missing-components to list of plugins

Closes GH-2442.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

Author: talatkuyuk

docs/docs/extending-mdx.mdx

@@ -71,9 +71,14 @@ See also the [list of remark plugins][remark-plugins] and
 
 * [`remcohaszing/recma-export-filepath`](https://github.com/remcohaszing/recma-export-filepath)
   — export the filepath
+* [`ipikuka/recma-mdx-change-props`](https://github.com/ipikuka/recma-mdx-change-props)
+  — changes the param as `_props` in the `_createMdxContent` function
 * [`domdomegg/recma-mdx-displayname`](https://github.com/domdomegg/recma-mdx-displayname)
   — add a `displayName` to `MDXContent` components, to enable switching
   on them in production
+* [`ipikuka/recma-mdx-escape-missing-components`](https://github.com/ipikuka/recma-mdx-escape-missing-components)
+  — set a default value of `() => null` for missing components instead of
+  throwing an error
 * [`remcohaszing/recma-mdx-is-mdx-component`](https://github.com/remcohaszing/recma-mdx-is-mdx-component)
   — add an `isMdxComponent` field on MDX components
 * [`remcohaszing/recma-nextjs-static-props`](https://github.com/remcohaszing/recma-nextjs-static-props)