misc: add note about edits in versioned docs

CONTRIBUTING.md

@@ -32,6 +32,8 @@ If you only want to make content changes you just need to know about versioned d
 
 To make a fix to the published versions you must edit the corresponding markdown file in both folders. If you only made changes in `docs`, be sure to be viewing the `next` version to see the updates (ensure there's `next` in the URL).
 
+> Do not edit the auto-generated files within `versioned_docs/` or `versioned_sidebars/` unless you are sure it is necessary. For example, information about new features should not be documented in versioned docs. Edits made to older versions will not be propagated to newer versions of the docs.
+
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