socket: Add a simple println when SendQ exceeded, config comment update

irc/socket.go

 			}
 			if socket.MaxSendQBytes < sendQBytes {
 				socket.conn.Write([]byte("\r\nERROR :SendQ Exceeded\r\n"))
+				fmt.Println("SendQ exceeded, disconnected client")
 				break
 			}
 

oragono.yaml

     motd: oragono.motd
 
     # maximum length of clients' sendQ in bytes
+    # this should be big enough to hold /LIST and HELP replies
     max-sendq: 16k
 
     # maximum number of connections per subnet