docs: Update openID client userinfo usage

[LudvigHz]

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Other, please describe: Documentation

The documentation on obtaining userinfo through the OpenID userinfo endpoint seems to be incorrect,
as the userinfo method both does not expect positional arguments, and the request should in all
cases require a token?

I would suggest changing the function signature to include the token kwarg explicitly, as it is in
the request method. Let me know and I'll update this PR to include that as well.

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[lepture]

Thanks