Add example information

Author: pennam

src/ArduinoIoTCloudTCP.h

@@ -85,6 +85,7 @@ class ArduinoIoTCloudTCP: public ArduinoIoTCloudClass
 #if OTA_ENABLED
     /* The callback is triggered when the OTA is initiated and it gets executed until _ota_req flag is cleared.
      * It should return true when the OTA can be applied or false otherwise.
+     * See example ArduinoIoTCloud-DeferredOTA.ino
      */
     void onOTARequestCb(otaConfirmationStatus cb) {
       _get_ota_confirmation = cb;