Review PR template: readiness-note fix and RM reviewer-assignment action

release_automation/templates/pr_bodies/release_review_pr.mustache

@@ -16,7 +16,7 @@ Edit and review this PR before merging it into the release snapshot. After Codeo
 
 ### Codeowner Actions
 
-_Tick each box once done. Release Management review starts when all three boxes are ticked._
+_Tick each box once done. Ticking the last box — "The release is ready for Release Management review" — starts the Release Management review._
 
 - [ ] **Update the CHANGELOG**
 
@@ -45,6 +45,9 @@ _Tick each box once done. Release Management review starts when all three boxes
 
 ### Release Management Actions
 
+_The following actions and checks are done by a Release Management reviewer before approving the PR:_
+
+- [ ] **Assign the Release Management reviewer(s) as assignee(s) of this PR**
 - [ ] CHANGELOG follows the release documentation rules
 - [ ] Breaking changes are documented and version updates follow SemVer rules
 - [ ] Mandatory release assets are present for each API according to its status

release_automation/tests/test_template_loader.py

@@ -47,6 +47,8 @@ def test_render_release_review_pr_template(self):
         assert "Commonalities r3.4" in result
         assert "Mandatory release assets are present for each API according to its status" in result
         assert "All remaining validation warnings are documented in issues and the reasons for deferral are defensible" in result
+        assert "Assign the Release Management reviewer(s) as assignee(s) of this PR" in result
+        assert "The following actions and checks are done by a Release Management reviewer before approving the PR" in result
         assert "### Valid next actions for codeowners" in result
         assert "Snapshot: [`r4.1-abc1234`]" in result
         assert "<details>" in result