message: Update CONTRIBUTING.md after webpack bundling addition
  With the addition of Webpack bundling (issue commit 1f80b2d4c)
  the instructions for how to run tests were no longer working.
diff: @@ -46,7 +46,8 @@ When submitting a PR, please fill out the template that is presented by GitHub w
  # Or run tests by selecting the appropriate drop down option
  # Alternatively, build and run tests through gulp and npm scripts
  - gulp build # build
  + gulp build # build extension
  + gulp prepare-test # build sources and tests
  npm test # test (must close all instances of VSCode)
  # Only available if Docker is installed and running
  