Add link to generated rust docs

Change-Id: I4f2ea4fcadb2792a701adbb43437a60a2b1758ca
diff --git a/public/index.html b/public/index.html
index 1efb458..308c383 100644
--- a/public/index.html
+++ b/public/index.html
@@ -24,6 +24,7 @@
   <h5><span>Languages</span></h5>
   <ul>
         <li><a href="dart/index.html">Dart APIs</a></li>
+        <li><a href="rust/auth_cache/index.html">Rust APIs</a></li>
   </ul>
 </div>