Put comma after If possible

Author: fatosmorina

README.md

@@ -49,7 +49,7 @@ This repo contains the source code and documentation powering [reactjs.org](http
 1. `git push my-fork-name the-name-of-my-branch`
 1. Go to the [reactjs.org repo](https://github.com/reactjs/reactjs.org) and you should see recently pushed branches.
 1. Follow GitHub's instructions.
-1. If possible include screenshots of visual changes. A Netlify build will also be automatically created once you make your PR so other people can see your change.
+1. If possible, include screenshots of visual changes. A Netlify build will also be automatically created once you make your PR so other people can see your change.
 
 ## Troubleshooting