nginx service: reduce restart time

roles/matrix-nginx-proxy/templates/systemd/matrix-nginx-proxy.service.j2

@@ -47,7 +47,7 @@ ExecStart=/usr/bin/docker run --rm --name matrix-nginx-proxy \
 #ExecStop=-/usr/bin/docker rm matrix-nginx-proxy
 ExecReload=/usr/bin/docker exec matrix-nginx-proxy /usr/sbin/nginx -s reload
 Restart=always
-RestartSec=30
+RestartSec=15
 SyslogIdentifier=matrix-nginx-proxy
 
 [Install]