notes/merging.md: --why now has a fourth output, and its list still says three nf-gdvd ← Beads

Twinned from https://github.com/cfsh/ninefold/issues/856 by tools/beads/import_github.py's reconcile pass.

notes/merging.md (lines ~85–102) describes merge_pr.py --why as answering *"for three refusals, not one"* and enumerates them.

Since #853 there is a fourth always-printed output, and it is deliberately not a refusal: one line reporting the reviewer's standing verdict as an answer — reviewer: CONVERGED at <sha> — a successful terminal state, not a lesser PASS, or the rev:off / GAPS / no-verdict / stale-green forms of it.

So a session reading that section never learns the line exists, which matters because the line's whole job is to be read at the moment a coder decides whether to go round again (#844).

One bullet in that list. ⚠️ notes/merging.md is perimeter.GOVERNANCE — it is this gate's own specification — so whoever takes it needs @aedanpope's approval.

Raised by the Tier-0 pass on #853 and filed rather than folded in, to keep that PR to part (d) of #844 (*"avoid scope creep"*, @aedanpope on #844).

Refs #844, #853.