Mark lines with changes

Author: rickbeerendonk

site/jekyll/getting-started/tutorial.md

@@ -593,7 +593,7 @@ var CommentForm = React.createClass({
 
 Let's make the form interactive. When the user submits the form, we should clear it, submit a request to the server, and refresh the list of comments. To start, let's listen for the form's submit event and clear it.
 
-```javascript{2-13,16}
+```javascript{2-13,16-18}
 var CommentForm = React.createClass({
   handleSubmit: function(e) {
     e.preventDefault();