docs(auth): add information about error codes for verifyBeforeUpdateEmail

[Lyokone]

Description

Taken from https://firebase.google.com/docs/reference/js/v8/firebase.User#verifybeforeupdateemail

Related Issues

closes #11801

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[russellwheatley]

LGTM - but I think it needs to be copy/pasted for the Platform Interface method as well 🙏