Add comment about updating to a newer Hugo version

.github/workflows/build-and-deploy.yaml

@@ -54,6 +54,8 @@ jobs:
       # NOTE: It sometimes happens that new Hugo versions break the site. So I've decided to always
       #   "pin" the Hugo version (instead of using the latest version). This way, the Hugo version
       #   can be updated with a pull request where I can test the new version.
+      # IMPORTANT: Always use a pull request to update the Hugo version to be able to fix all problems
+      #   before pushing the result to production!!!
       HUGO_VERSION: 0.122.0
 
       # The directory in which Hugo stores the generated site.