docs: fix prettier script command in pull_request_template.md (#310)

.github/pull_request_template.md

@@ -7,7 +7,7 @@ Hello, and thanks for contributing to react-imgix! 🎉🙌
 2.  Run `npm install` in the repository root.
 3.  If you've fixed a bug or added code that should be tested, add tests!
 4.  Ensure the test suite passes (`npm run test`). Tip: `npm run --watch` is helpful in development.
-5.  Format your code with [prettier](https://github.com/prettier/prettier) (`npm run format`). Don't worry too much if you haven't done this, we have a bot that will do this for you when you submit a PR.
+5.  Format your code with [prettier](https://github.com/prettier/prettier) (`npm run pretty`). Don't worry too much if you haven't done this, we have a bot that will do this for you when you submit a PR.
 6.  Fill out the template below and delete everything above the line.
 
 **Learn more about contributing:** https://github.com/imgix/react-imgix/blob/master/CONTRIBUTING.md