[SX126x] Added note about TCXO modules

examples/SX126x/SX126x_Transmit/SX126x_Transmit.ino

@@ -38,6 +38,27 @@ void setup() {
     Serial.println(state);
     while (true);
   }
+
+  // NOTE: Some SX126x modules use TCXO
+  //       (Temprature-Compensated Crystal Oscillator).
+  //       To be able to use these modules, TCXO
+  //       control must be enabled by calling
+  //       setTCXO() and specifying the reference
+  //       voltage.
+  /*
+  Serial.print(F("[SX1262] Setting TCXO reference ... "));
+  // enable TCXO
+  // reference voltage:           1.6 V
+  // timeout:                     5000 us
+  state = lora.setTCXO(1.6);
+  if (state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while (true);
+  }
+  */
 }
 
 void loop() {