;ci: release: try to fix over-active release creation

.github/workflows/release.yml

@@ -1,14 +1,16 @@
-# Runs on push of a [0-9]* or r[0-9]* tag.
+# Runs on push of a [0-9]* or r[0-9]* tag (to any branch ?)
 
 # Creates a draft github release.
 # See https://github.com/actions/create-release, still pretty rough as of 20200609.
+# see also: https://github.com/marketplace/actions/tag-release-on-push-action
 
 name: release
 
+# https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#onpushpull_requestbranchestags
+# also: "The action does not seem to work for tags created before the workflow."
 on:
   push:
     tags: [ '[0-9]*', 'r[0-9]*' ]
-    branches: [ 'master', '[0-9]*-branch' ]
 
 jobs:
   release: