[docs] Fix line highlights for linked-state-mixin

docs/10.2-form-input-binding-sugar.md

@@ -45,7 +45,7 @@ var NoLink = React.createClass({
 
 This works really well and it's very clear how data is flowing, however, with a lot of form fields it could get a bit verbose. Let's use `ReactLink` to save us some typing:
 
-```javascript{2,7}
+```javascript{4,9}
 var LinkedStateMixin = require('react-addons-linked-state-mixin');
 
 var WithLink = React.createClass({