Built-in extension: informing about translation progress

Is your feature request related to a problem? Please describe. Sphinx projects which are being translated into multiple languages using Gettext, when a translation is still in progress, display original paragraphs as a fallback to missing translations of paragraphs. That could be unexpected for a reader looking at a project in some language (which for example can be translated in a majority of content).

Describe the solution you'd like Built-in extension to enable displaying a note paragraph at the top of every article that is not fully translated, informing a reader about the progress of the translation in the article.

Would such an extension be accepted as a built-in?

Describe alternatives you've considered

• third party extension – in my opinion the described functionality being accessible as batteries-included inside Sphinx would be beneficial to many projects around, as publishing the in progress translations seems to be a quite common case for projects using intl

Additional context

• https://github.com/python/docsbuild-scripts/issues/148
• related/ground work
  • https://github.com/sphinx-doc/sphinx/issues/11157 (https://github.com/sphinx-doc/sphinx/pull/11502)
  • https://github.com/sphinx-doc/sphinx/pull/11509