Update protocol doc to point to the right location.

Author: Kailash Sethuraman

_includes/nav.html

@@ -20,10 +20,10 @@
         <li><a href="/docs/">Documentation</a></li>
         <li><a href="/contribute/">Contribute</a></li>
         <li><a href="/faq/">FAQ</a></li>
-        <li><a href="https://github.com/grpc/grpc-common/blob/master/PROTOCOL-HTTP2.md">Protocol</a></li>
+        <li><a href="https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md">Protocol</a></li>
         <!-- Hide link to blog until we have actual posts -->
         <!-- <li><a href="/blog/" title="">Blog</a></li> -->
       </ul>
     </div><!-- /.navbar-collapse -->
   </div><!-- /.container-fluid -->
-</nav>
+</nav>