Add ``last updated`` for document (#11164)
## Summary
Display the last document update time, excluding any automatically
generated parts of the document, while ensuring that Google can
accurately read and recognize the webpage's time.
Note that I do not have permission to update
``requirements-insiders.txt``
Google time info
*
https://developers.google.com/search/blog/2019/03/help-google-search-know-best-date-for
*
https://developers.google.com/search/docs/appearance/structured-data/article#amp
Similar https://github.com/astral-sh/uv/pull/11162
Closes #11148
## Test Plan
uvx --with-requirements docs/requirements.txt -- mkdocs serve -f
mkdocs.public.yml --strict
The correct format is actually ``2024-08-08T22:01:08Z``, but Google
Search happens to be lenient and accepts this format.
main.html
requirements.txt