add commented-out PrivateNetwork to unit file

distrib/systemd/oragono.service

@@ -15,6 +15,8 @@ ExecStart=/home/oragono/oragono run --conf /home/oragono/ircd.yaml
 ExecReload=/bin/kill -HUP $MAINPID
 Restart=on-failure
 LimitNOFILE=1048576
+# Uncomment this for a hidden service:
+# PrivateNetwork=true
 
 [Install]
 WantedBy=multi-user.target