Updated the release checklist documentation

docs/release_checklist.md

@@ -9,6 +9,8 @@
   to have GitHub Actions create release assets. This makes sure the revision
   string baked into the archives is correct.
 
+* Verify that the source archive REVISION.txt has the correct release tag.
+
 * Create a GitHub release and attach the archives you just generated.
 
 ## New feature release