add example caddyfile and systemd service

examples/Caddyfile

@@ -0,0 +1,6 @@
+publapi.yourdomain.tld {
+	reverse_proxy localhost:3000
+	basicauth /signup
+		admin xxx
+	}
+}

examples/publapi.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=API for the Project Segfault Pubnix
+After=networking.target
+[Service]
+WorkingDirectory=/var/publapi
+User=publapi
+Group=publapi
+Environment=PUBLAPI_PORT=3000
+Environment=SHOUTRRR_URL='matrix://user:password@host/'
+ExecStart=/var/publapi/publapi
+RestartSec=5
+Restart=always
+KillMode=mixed
+
+[Install]
+WantedBy=default.target