Removing "disabled" class from link.

Author: mugurm

_layouts/docs.html

@@ -11,7 +11,7 @@
       <li><a class="disabled" href="/docs/guides/concepts.html">gRPC concepts</a></li>
       <li><a href="/docs/guides/auth.html">Authentication</a></li>
       <li><a class="disabled" href="/docs/guides/tuning.html">Tuning RPC behaviour</a></li>
-      <li><a class="disabled" href="https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md">Wire format</a></li>
+      <li><a href="https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md">Wire format</a></li>
       <li><a class="disabled" href="/docs/guides/error.html">Error handling and debugging</a></li>
       <li><a class="disabled" href="/docs/guides/contributing.html">Contribution guidelines</a></li>
       <li><h4>Quick Start</h4></li>