Add auto-label configuration for the docker label

Add a configuration to automatically apply the `docker` label to pull
requests.

Author: mcdonnnj

.github/labeler.yml

@@ -19,6 +19,13 @@ dependencies:
           # Add any dependency files used.
           - .pre-commit-config.yaml
           - requirements*.txt
+# Enable if Docker is used in the repository.
+# docker:
+#   - changed-files:
+#       - any-glob-to-any-file:
+#           - "**/compose*.yml"
+#           - "**/docker-compose*.yml"
+#           - "**/Dockerfile*"
 documentation:
   - changed-files:
       - any-glob-to-any-file: