Fix fmt call

cmd/publisher/main.go

@@ -22,7 +22,7 @@ func main() {
 		fmt.Printf("Received Message: %s from topic %s\n", msg.Payload(), msg.Topic())
 	})
 	options.OnConnect = func(c mqtt.Client) { fmt.Println("Connected to Broker") }
-	options.OnConnectionLost = func(c mqtt.Client, err error) { fmt.Println("Connection Lost: %v", err) }
+	options.OnConnectionLost = func(c mqtt.Client, err error) { fmt.Printf("Connection Lost: %v\n", err) }
 	client := mqtt.NewClient(options)
 	if token := client.Connect(); token.Wait() && token.Error() != nil {
 		panic(token.Error())