Feature request: display link that redirects back to corresponding doc link at PR review's 404 page

[jasonren0403]

When proposing PR on content/translated-content repo, only the content that proposed changes are served(and they are at prxxxx.content.dev.mdn.mozit.cloud). Therefore, it may be useful for some links in documents jump to original web docs' page, in that case I wouldn't copy and change the URL manually when reaching 404 errors:(

Can we display notices like "You are now at developement website of developer.mozilla.org, redirect you back to correspoding document?(or better messages possible)" at 404 pages on developement site(which created by PRs)and show links to original version of document if possible?

Edit: I do a little mocking to clarify what I said:

[caugner]

For now, I can think of two solutions:

1. Read the index.json from https://developer.mozilla.org/
2. Rewrite links to https://developer.mozilla.org (but this is tricky, because you might navigate back to the reviewed page via the sidebar, and suddenly you don't see the PR version).