docs: pin verification receipt scope in change control

Author: LalaSkye

docs/governance/CHANGE_CONTROL.md

@@ -16,6 +16,7 @@ A receipt entry **must** be added to `docs/governance/BUILD_RECEIPTS.md` when a
 4. Adds, removes, or modifies a claim in `ADMISSIBLE_CLAIM_REGISTER_v1.md`
 5. Changes the CI workflow in a way that affects enforcement scope
 6. Changes the PR template in a way that affects contributor obligations
+7. Adds, removes, or modifies a receipt scope boundary in `VERIFICATION_RECEIPT_SCOPE.md`
 
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@@ -26,6 +27,7 @@ The standing claim boundary **must** be re-stated (not silently widened) when a
 1. Promotes a configured surface to an evidenced one (e.g. CI green proof)
 2. Adds a new proof surface visible from README or entry
 3. Removes or weakens an existing proof surface
+4. Changes what a verification receipt is allowed to prove
 
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