Explicity indicate the socket unit to use the service unit "gitea.service" (#8804)

* rename socket file, make example more precise, use long parameter name

* correct path

* use the correct path to the configuration file according to the documentation

* rename the socket unit back to 'gitea.main.socket', explicitly indicate that the socket unit should use the service file 'gitea.service'

contrib/systemd/gitea.service

@@ -30,7 +30,8 @@ After=network.target
 ## PartOf=gitea.service
 ##
 ## [Socket]
-## ListenStream=
+## Service=gitea.service
+## ListenStream=<some_port>
 ## NoDelay=true
 ##
 ## [Install]
@@ -53,7 +54,7 @@ WorkingDirectory=/var/lib/gitea/
 # If using unix socket: Tells Systemd to create /run/gitea folder to home gitea.sock
 # Manual cration would vanish after reboot.
 #RuntimeDirectory=gitea
-ExecStart=/usr/local/bin/gitea web -c /etc/gitea/app.ini
+ExecStart=/usr/local/bin/gitea web --config /etc/gitea/app.ini
 Restart=always
 Environment=USER=git HOME=/home/git GITEA_WORK_DIR=/var/lib/gitea
 # If you want to bind Gitea to a port below 1024, uncomment