Remove broken link to removed 'Async Data' example

Author: Sabra Pratt

examples/index.html

@@ -5,7 +5,6 @@
 <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="dynamic-segments/index.html">Dynamic Segments</a></li>
 <li><a href="huge-apps/index.html">Huge Apps (Partial App Loading)</a></li>