docs: document purpose of second workflow file via comments.

Signed-off-by: Matthew Weier O'Phinney <matthew@weierophinney.net>

examples/.github/workflows/release-on-milestone-closed-triggering-release-event.yml

@@ -1,4 +1,8 @@
-# https://help.github.com/en/categories/automating-your-workflow-with-github-actions
+# Alternate workflow example.
+# This one is identical to the one in release-on-milestone.yml, with one change:
+# the Release step uses the ORGANIZATION_ADMIN_TOKEN instead, to allow it to
+# trigger a release workflow event. This is useful if you have other actions
+# that intercept that event.
 
 name: "Automatic Releases"