fix(ringoverlay): Path of the ogg file

modules/UI/ring_overlay/RingOverlay.js

                         <p>${callee.getName()}${callerStateLabel}</p>
                     </div>
                 </div>
-                <audio id="${this._audioContainerId}" src="/sounds/ring.ogg" />
+                <audio id="${this._audioContainerId}" src="./sounds/ring.ogg" />
             </div>`;
     }