Add async-data example to examples index page

Author: mjackson

examples/index.html

@@ -5,6 +5,7 @@
 <h1>React Router Examples</h1>
 <ul>
 <li><a href="animations/index.html">Animations</a></li>
+<li><a href="async-data/index.html">Async Data</a></li>
 <li><a href="auth-flow/index.html">Auth Flow</a></li>
 <li><a href="data-flow/index.html">Data Flow</a></li>
 <li><a href="dynamic-segments/index.html">Dynamic Segments</a></li>