title: Gitlab CI - How to trigger a build only if changes happen on particular set of files
body: <p>In Gitlab CI, how do you trigger a build only if changes happen on particular set of files?</p>
  
  <p>Is there a way to either include or exclude certain files from triggering a build? For eg: updating <code>README.md, .gitignore</code> files should not cause a build to trigger.</p>