Move threading.local docs from docstring to the docs

[nedbat]

Documentation

https://docs.python.org/3/library/threading.html#threading.local says:

For more details and extensive examples, see the documentation string of the _threading_local module: Lib/_threading_local.py.

If we have good helpful words about a component in the standard library, we should publish them in the docs. The docstring should be moved to the .rst file, or at least parts harvested.

Linked PRs

• gh-107006: Move threading.local docstring to docs #131840
• [3.13] gh-107006: Move threading.local docstring to docs (GH-131840) #133432

[mdickinson]

Yes, please! It would be particularly useful to have the pattern of subclassing threading.local available in the docs.

[hugovk]

Thanks all, this is now done.