mqtt: added example configuration

etc/example.conf

@@ -302,6 +302,29 @@ nodes = {
 				"int32"
 			]
 		}
+	},
+	mqtt_node = {
+		type = "mqtt",
+		
+		format = "protobuf",
+		
+		host = "localhost",
+		port = 1883,
+		
+		keepalive = 5,				# Send ping every 5 seconds to keep connection alive
+		retain = false,
+		qos = 0,
+
+		publish = "test-topic",
+		subscribe = "test-topic",
+		
+		ssl = {
+			enabled = false,
+			insecure = true,
+			cafile = "/etc/ssl/certs/ca-bundle.crt",
+			certfile = "/etc/ssl/certs/my.crt",
+			keyfile = "/etc/ssl/keys/my.key"
+		}
 	}
 };