Rename FF, add documentation note

What does this MR do and why?

Renames FF, adds documentation note

Related: #388128 (closed), [MVC] Branch Rules Editing (&8075)

Changelog: changed

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

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Before	After

How to set up and validate locally

Enable "edit_branch_rules" ff, make sure that Create from dropdown, edit, delete BR still works