Document ci-unit-tests-docker.patch.yml

.github/workflows/ci-unit-tests-docker.patch.yml

@@ -1,7 +1,7 @@
+# Workflow patches for skipping CI when Rust code and dependencies aren't modified in a PR.
 name: Docker Unit Tests
 
-# These jobs *don't* depend on cached Google Cloud state disks,
-# so they can be skipped when the modified files make the actual workflow run.
+# Run on PRs with unmodified code and dependency files.
 on:
   pull_request:
     paths-ignore:
@@ -25,6 +25,9 @@ on:
       - '.github/workflows/sub-find-cached-disks.yml'
       - '.github/workflows/sub-build-docker-image.yml'
 
+# IMPORTANT
+#
+# These job names must be kept in sync with the `.patch-external.yml` and `.yml` files.
 jobs:
   build:
     name: Build CI Docker / Build images