Fix example code

Summary: Closes https://github.com/facebook/react-native/pull/12908

Differential Revision: D4701705

Pulled By: hramos

fbshipit-source-id: 9ac33e57e0df73b4b8a0d1a05a4254e7482e2ef6

blog/2017-03-13-better-list-views.md

@@ -17,7 +17,7 @@ This is the workhorse component for simple, performant lists. Provide an array o
 ```
 <FlatList
   data={[{title: 'Title Text', key: 'item1'}, ...]}
-  renderItem={({item}) => <ListItem title={item.title}}
+  renderItem={({item}) => <ListItem title={item.title} />}
 />
 ```