Added p5.MediaElement.src example

lib/addons/p5.dom.js

@@ -1752,6 +1752,40 @@
      *
      *  @property src
      *  @return {String} src
+     *  @example
+     *  <div><code>
+     *  var ele;
+     *
+     *  function setup() {
+     *    background(250);
+     *
+     *    //p5.MediaElement objects are usually created
+     *    //by calling the createAudio(), createVideo(),
+     *    //and createCapture() functions.
+     *
+     *    //In this example we create
+     *    //a new p5.MediaElement via createAudio().
+     *    ele = createAudio('assets/beat.mp3');
+     *
+     *    //We'll set up our example so that
+     *    //when you click on the text,
+     *    //an alert box displays the MediaElement's
+     *    //src field.
+     *    textAlign(CENTER);
+     *    text("Click Me!", width/2, height/2);
+     *  }
+     *
+     *  function mouseClicked() {
+     *    //here we test if the mouse is over the
+     *    //canvas element when it's clicked
+     *    if(mouseX >= 0 && mouseX <= width &&
+     *      mouseY >= 0 && mouseY <= height) {
+     *      //Show our p5.MediaElement's src field
+     *      alert(ele.src);
+     *    }
+     *  }
+     *
+     *  </code></div>
      */
     Object.defineProperty(self, 'src', {
       get: function() {