Added docs type definition for audiosprite sound object

Author: pavle-goloskokovic

src/sound/BaseSoundManager.js

@@ -193,6 +193,14 @@ var BaseSoundManager = new Class({
      */
     add: NOOP,
 
+    /**
+     * Audio sprite sound type.
+     *
+     * @typedef {Phaser.Sound.BaseSound} AudioSpriteSound
+     *
+     * @property {object} spritemap - Local reference to 'spritemap' object form json file generated by audiosprite tool.
+     */
+
     /**
      * Adds a new audio sprite sound into the sound manager.
      *