subscriber's id print

MQTTSample/MqttSubscriberApp/Program.cs

@@ -37,7 +37,7 @@ namespace MqttSubscriberApp
 
         private static async Task MqttClient_ConnectedAsync(MqttClientConnectedEventArgs arg)
         {
-            Console.WriteLine("Connected to broker.");
+            Console.WriteLine($"Connected to broker with ID: [{CLIENT_ID}].");
 
             await _mqttClient.SubscribeAsync(new MqttTopicFilterBuilder()
                 .WithTopic(TOPIC)