maintain: document azure oidc config

[BruceMacD]

• azure oidc app config, no groups
• okta doc update

Summary

This documents setting up Azure as an identity provider. Group sync is not yet supported. Also some small clean-up of the Okta docs.

Checklist

• Wrote appropriate unit tests
• Considered security implications of the change
• Updated associated docs where necessary
• Updated associated configuration where necessary
• Change is backwards compatible if it needs to be (user can upgrade without manual steps?)
• Nothing sensitive logged
• Considered data migrations for smooth upgrades

Related Issues

Part of #2220