Add newline to end of frontend.md.

doc/development/frontend.md

@@ -438,4 +438,4 @@ Scenario: Developer can approve merge request
 [vue-resource-repo]: https://github.com/pagekit/vue-resource
 [issue-boards-service]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/javascripts/boards/services/board_service.js.es6
 [airbnb-js-style-guide]: https://github.com/airbnb/javascript
-[eslintrc]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/.eslintrc
\ No newline at end of file
+[eslintrc]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/.eslintrc