Give the Rollout Checkbox a Mechanically Real Owner

docs/pre-commit-hooks-rollout.md

@@ -8,10 +8,11 @@ not a restatement of the rule. It is **hub-only** and is not carried downstream,
 [`docs/eol-lf-rollout.md`][eol-lf-rollout] is hub-only, because it tracks the hub's own migration
 rather than a fact a downstream repo's own docs need to carry.
 
-**Maintenance rule.** Check a repo's box in the same pull request that converts it, via the
-normal `resync-a-repo` procedure, once that repo's own audit reports `parity.hooks` operational.
-A register showing a repo unchecked after its conversion PR merged is itself stale prose, so this
-doc is only trustworthy while that rule holds.
+**Maintenance rule.** This file is hub-only, so a downstream repo's own conversion PR cannot edit
+it. Check a repo's box in its own small hub-side PR, opened as part of the same `resync-a-repo`
+session that converts the downstream repo, once that repo's own audit reports `parity.hooks`
+operational. A register showing a repo unchecked after its conversion PR merged is itself stale
+prose, so this doc is only trustworthy while that rule holds.
 
 ## What Changed
 
@@ -39,7 +40,8 @@ Open the PR through the repo's normal branching model.
 A repo whose corpus does not yet pass its language formatter clean ships the doc-gate half first
 and adds the language half once it does, per the mid-convergence carve-out. That partial state is
 not a reason to leave the box unchecked, since the doc-gate half alone already satisfies
-`parity.hooks`' intent tier. Check the box below in this same PR, before it merges, per the maintenance rule above.
+`parity.hooks`' intent tier. Once the downstream PR merges, open the small hub-side PR the
+maintenance rule above describes and check the box below in it.
 
 A repo declaring neither `csharp` nor `python` in `registry/repos.json` (the `eda` repos, and any
 repo with no fleet-covered language) has no language-format half to add: the doc-gate half alone