message: CONTRIBUTING: ask to quote python stacktraces
diff: @@ -18,6 +18,9 @@ If you are reporting a bug, please include:
  troubleshooting.
  - Detailed steps to reproduce the bug.
  +When you post python stack traces please quote them using
  +[markdown blocks](https://help.github.com/articles/creating-and-highlighting-code-blocks/).
  +
  ### Fix Bugs
  Look through the GitHub issues for bugs. Anything tagged with "bug" is
  