Fix documentation for server implementation

[Bruce-Hopkins]

I noticed two issues with the server code example:

1. The documentation for the server implementation includes the line server.ws

   But in documentation, we don't console.log the port like we do HTTP and UTP:

   server.on('listening', function () {
   // fired when all requested servers are listening
   console.log('listening on http port:' + server.http.address().port)
   console.log('listening on udp port:' + server.udp.address().port)
   })

2. The three variables being used on the server.listen() function are not defined.

   server.listen(port, hostname, onlistening)

   Can I add these to the doc?