Add Debian example systemd service

Signed-off-by: Valerian Saliou <valerian@valeriansaliou.name>

examples/config/systemd.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=Vigil Microservices Status Page
+After=network.target
+
+[Service]
+Type=simple
+User=vigil
+Group=vigil
+ExecStartPre=/sbin/setcap 'cap_net_raw+ep' /bin/vigil
+ExecStart=/bin/vigil -c /etc/vigil.cfg
+Restart=on-failure
+
+[Install]
+WantedBy=multi-user.target