"Google Docstring Format" link goes to 404

[BruceEckel]

Under this header: https://trio.readthedocs.io/en/stable/contributing.html#documentation At the beginning of the 2nd paragraph: "For docstrings, we use the Google docstring format."

The link goes to a 404 page.

[A5rocks]

It looks like v3 of the Sphinx docs was pulled? This link certainly works: https://www.sphinx-doc.org/en/master/usage/extensions/example_google.html#example-google-style-python-docstrings

~~I think we should probably check the old link 404ing is intentional.~~ It must have been, v4 was released in roughly (not exactly) right timeframe for this to happen. Nonetheless, updating our docs should be simple.

[kachida]

Hi @A5rocks , I've created a pull request (PR#2967) for this issue. Could you please take a look and review it

https://github.com/python-trio/trio/pull/2967