The reason codes POST /v2/search/feedback accepts in reasons[].code, and the
requirement flag codes POST /v2/search/feedback/query accepts in flags[].codes.
Show label to users and description as a hint. Offer the reason codes whose
rating matches the user's rating (both lists for maybe) and keep a free-text field
next to them: other is part of each list for reasons the codes do not cover.

version changes whenever the lists change; codes are never reused with a
different meaning.