Update example code in README.md (#531)

Author: Vitalik7

README.md

@@ -84,9 +84,8 @@ var whoosh = new Sound('whoosh.mp3', Sound.MAIN_BUNDLE, (error) => {
   }
   // loaded successfully
   console.log('duration in seconds: ' + whoosh.getDuration() + 'number of channels: ' + whoosh.getNumberOfChannels());
-});
-
-// Play the sound with an onEnd callback
+  
+  // Play the sound with an onEnd callback
 whoosh.play((success) => {
   if (success) {
     console.log('successfully finished playing');
@@ -97,6 +96,7 @@ whoosh.play((success) => {
     whoosh.reset();
   }
 });
+});
 
 // Reduce the volume by half
 whoosh.setVolume(0.5);