Provide small debug string make sure which is client and which is server.

Author: aentinger

examples/UDP_Client/UDP_Client.ino

@@ -107,6 +107,8 @@ void setup()
     Serial.println("begin(...) failed for UDP server");
     for (;;) { }
   }
+
+  Serial.println("UDP_Client");
 }
 
 void loop()

examples/UDP_Server/UDP_Server.ino

@@ -110,6 +110,8 @@ void setup()
     Serial.println("begin(...) failed for UDP server");
     for (;;) { }
   }
+
+  Serial.println("UDP_Server");
 }
 
 void loop()