Update docs to reflect new overflow menu on user profile

What does this MR do and why?

For #414773 (closed)

Document moving user profile options into an overflow menu.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable user_profile_overflow_menu_vue feature flag
   • bin/rails console
   • Feature.enable(:user_profile_overflow_menu_vue)

MR acceptance checklist

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