Let a newer Deploy Docs run cancel the one in progress

A run that never gets a runner held the deploy-docs concurrency group, so
every later deploy waited behind it and the site went stale. Each run builds
the tips of main and v1.x, so the newest run publishes everything.

Author: maxisbey

.github/workflows/deploy-docs.yml

@@ -26,7 +26,12 @@ on:
 
 concurrency:
   group: deploy-docs
-  cancel-in-progress: false
+  # Newest run wins. build-docs.sh builds the tips of main and v1.x, not the
+  # triggering commit, so a newer run publishes everything an older one would,
+  # and Pages takes the site as one artifact, so a cancelled run leaves the live
+  # site as it was. With `false`, a run that never gets a runner holds the group
+  # and every later deploy waits behind it.
+  cancel-in-progress: true
 
 jobs:
   deploy-docs: