docs/: Add example override config file

docs/config-EXAMPLE.json

@@ -0,0 +1,12 @@
+{
+	"CERT_FILE": "/home/eddn/etc/fullchain.pem",
+	"KEY_FILE": "/home/eddn/etc/privkey.pem",
+
+	"GATEWAY_HTTP_BIND_ADDRESS": "0.0.0.0",
+
+	"MONITOR_DB": {
+		"database": "eddn",
+		"user": "eddn",
+		"password": "SOME SECURE PASSWORD"
+	},
+}