Move [GoAgent](https://trac.torproject.org/projects/tor/wiki/doc/GoAgent) to "things to know about" section. ([diff](https://trac.torproject.org/projects/tor/wiki/doc/PluggableTransports?action=diff&version=43)) URL: https://trac.torproject.org/projects/tor/wiki/doc/PluggableTransports?version=43