fix: fix code block in README.md (TheWidlarzGroup#1455)

(rebased from commit 80391d4)

README.md

@@ -1137,12 +1137,13 @@ zip -r -n .mp4 *.mp4 player.video.example.com
 <Video source={{uri: "background", mainVer: 1, patchVer: 0}} // Looks for .mp4 file (background.mp4) in the given expansion version.
        resizeMode="cover"           // Fill the whole screen at aspect ratio.
        style={styles.backgroundVideo} />
+```
 
 ### Load files with the RN Asset System
 
 The asset system [introduced in RN `0.14`](http://www.reactnative.com/react-native-v0-14-0-released/) allows loading image resources shared across iOS and Android without touching native code. As of RN `0.31` [the same is true](https://github.com/facebook/react-native/commit/91ff6868a554c4930fd5fda6ba8044dbd56c8374) of mp4 video assets for Android. As of [RN `0.33`](https://github.com/facebook/react-native/releases/tag/v0.33.0) iOS is also supported. Requires `react-native-video@0.9.0`.
 
-```
+```javascript
 <Video
   source={require('../assets/video/turntable.mp4')}
 />