example: update source code link

Author: goto-bus-stop

example/index.html

@@ -36,7 +36,7 @@ <h1>@u-wave/react-vimeo example</h1>
           <p>
             An example Vimeo player using <a href="https://facebook.github.io/react">React</a>
             and <a href="https://github.com/u-wave/react-vimeo">@u-wave/react-vimeo</a>.
-            <a href="https://github.com/u-wave/react-vimeo/tree/master/example">view source</a>
+            <a href="https://github.com/u-wave/react-vimeo/tree/default/example">view source</a>
           </p>
         </div>
       </div>