feat: add systemd service examples

systemd/stapps-proxy.service

@@ -0,0 +1,23 @@
+[Unit]
+Description=@openstapps/proxy
+Documentation=https://gitlab.com/openstapps/proxy
+After=network-online.target
+Requires=network-online.target
+OnFailure=stapps-unit-status-mail@%n.service
+
+[Service]
+ExecStart=/usr/bin/env docker run --rm --net="host" \
+  -v /var/run/docker.sock:/var/run/docker.sock \
+  -v /opt/stapps-compose/proxy/ssl/chain.crt:/etc/nginx/certs/ssl.crt \
+  -v /opt/stapps-compose/proxy/ssl/private.key:/etc/nginx/certs/ssl.key \
+  -v /opt/stapps-compose/proxy/static:/static \
+  registry.gitlab.com/openstapps/proxy/master
+StartLimitBurst=2
+StartLimitIntervalSec=100s
+Restart=always
+RestartSec=20s
+WorkingDirectory=/opt/stapps-compose/proxy
+User=root
+
+[Install]
+WantedBy=multi-user.target