Add documentation on how to disable keyring

[pradyunsg]

Based off #7200

Closes #7200
Fixes #6773

[pradyunsg]

@chrahunt @pfmoore @uranusjr Could one of you take a look at this?

[uranusjr]

Does keyring have existing documentation on how to disable it? If so, I would structure the section as

• If you have problems authenticating, try disabling keyring.
• Suggest keyring --disable.
• Refer to keyring’s documentation if this is not available.
• If everything else fails, try uninstalling keyring altogether (with caveats).

I think this would be more helpful to the general audience, while not shouldering too much responsibility to explain things. keyring maintainers are in a better position to troubleshoot anything more complicated than keyring --disable.

[pfmoore]

I'm not particularly comfortable suggesting that the user uninstall keyring - as the PR says, this could break other code. And I don't think we should do the job of documenting keyring¹. I'd suggest similar to @uranusjr

1. If you have problems, you can disable keyring with --disable if you have a sufficiently recent version of keyring.
2. If you have an old version, consider upgrading to get the --disable option.
3. If you still have issues, contact the keyring project or consult their documentation. We can add the project's PyPI URL here (there's no real project homepage other than a github page, and no specific docs page, so IMO the PyPI page is the best link).

¹ The keyring docs don't seem particularly good in this area - the --disable option isn't even mentioned in the docs as far as I can see.

[pradyunsg]

Sounds reasonable to me!