Add comment to workflow re: unexpected behavior of "liskin/gh-problem-matcher-wrap" action

Author: per1234

.github/workflows/check-python-task.yml

@@ -90,6 +90,8 @@ jobs:
         uses: liskin/gh-problem-matcher-wrap@v3
         with:
           linters: flake8
+          # Due to a quirk of the "liskin/gh-problem-matcher-wrap" action, the entire command must be on a single line
+          # (instead of being broken into multiple lines for readability).
           run: task python:lint
 
   formatting: