Add user_types config settings to schema and auto-generate documentation

[hughns]

This was missed during the original PR #18456 as it collided with #17892 actually landing.

Pull Request Checklist

• Pull request is based on the develop branch
• Pull request includes a changelog file. The entry should:
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• Code style is correct (run the linters)

[erikjohnston]

This was done in #18522

[erikjohnston]

We want this on the release branch

[erikjohnston]

Have cherry-picked from the other PR