Docs: clarify required parameters for revoke_roles

[shivaansh0610-LUFFY]

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Fixes #446

The docstring for plone.api.user.revoke_roles incorrectly suggested that
The authenticated user would be used when neither username nor user
was provided.

In reality, a MissingParameterError is raised. This PR updates the
documentation to reflect the actual behavior.

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📚 Documentation preview 📚: https://ploneapi--599.org.readthedocs.build/

[mister-roboto]

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[mister-roboto]

@shivaansh0610-LUFFY thanks for creating this Pull Request and helping to improve Plone!

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Happy hacking!

[shivaansh0610-LUFFY]

@jenkins-plone-org please run jobs

[davisagli]

From what I can see, the proposed change is just plain wrong. The implementation does what the old docstring said (if there is no user or username, we call get(username=None) which returns the current authenticated user)

It would be great to have a test added for this case, however.

[davisagli]

Ah, now I read the related issue #446 and I understand that it is not actually doing what the docstring says.

However: the discussion there makes it clear that we should fix the implementation and add a test, rather than simply update the documentation. Being able to revoke the current user's roles is a desired feature.