[docs]: fix the edit page buttton link in docs

[Mr-Sunglasses]

(Explain how this PR changes mypy.)

fix: #17870

Issue

The current docs edit the page button gives a 404.

What changes this PR does

This PR edits the sphinx config.py and configures the edit button url to the master branch of this repository.

[hauntsaninja]

Hm, I couldn't find a reference for these options. Is there one?

[Mr-Sunglasses]

Hm, I couldn't find a reference for these options. Is there one?

Yeah, I take the reference from cpython devguide repo here and the docs for the furo theme here

[hauntsaninja]

Thanks for the fix and the link! :-)

[Mr-Sunglasses]

@hauntsaninja Quick question about how the docs are currently working after the recent PR merge. The current behavior of the docs site is as follows:

When we view the latest branch, the "Edit" button is visible. This happens because Sphinx uses the GitHub repository link combined with the branch name to allow editing the specific source file of the documentation.

However, when we switch to the stable branch, the "Edit" button disappears. This is expected behavior with Sphinx since the stable docs are released using tags, and tagged releases aren't associated with branches that can be directly edited.

IMO, we need to further discuss whether this is the behavior we want or if we need to consider changing how we deploy our docs.

[hauntsaninja]

Feel free to open an issue or more PRs if you have some improvements you'd like to make! :-)
I'm not particularly knowledgeable about sphinx / rtd, so don't have any opinions