Added Go client library links to navigation bar
<a class="dropdown-item" href="/docs/latest/clients/Java">
Java
</a>
+ <a class="dropdown-item" href="/docs/latest/clients/go">
+ Go
+ </a>
<a class="dropdown-item" href="/docs/latest/clients/Python">
Python
</a>
<a class="dropdown-item" href="/api/admin">
Java admin Javadoc
</a>
+ <a class="dropdown-item" href="https://godoc.org/github.com/apache/incubator-pulsar/pulsar-client-go/pulsar">
+ GoDoc
+ </a>
<a class="dropdown-item" href="/api/pulsar-functions">
Pulsar Functions Java SDK
</a>
