fix: to fix the RFM pins declaration

Author: AndreaZGuz

examples/class_c_otaa_ack/class_c_otaa_ack.ino

@@ -16,13 +16,14 @@ char myStr[50];
 char outStr[255];
 byte recvStatus = 0;
 
+//To confirm the pins used to handle the communication with the LoRa module
 const sRFM_pins RFM_pins = {
-  .CS = SS,
-  .RST = RFM_RST, 
-  .DIO0 = RFM_DIO0,
-  .DIO1 = RFM_DIO1, 
-  .DIO2 = RFM_DIO2, 
-  .DIO5 = RFM_DIO5,
+  .CS = 7,
+  .RST = 3, 
+  .DIO0 = 18,
+  .DIO1 = 19, 
+  /*.DIO2 = if_needed, 
+  .DIO5 = if_needed,*/
 };
 
 void setup() {