feat(uart): adds commentatries

Added functions for UART pins signal inversion.

Author: SuGlider

cores/esp32/HardwareSerial.h

@@ -348,6 +348,7 @@ class HardwareSerial : public Stream {
 
   void setDebugOutput(bool);
 
+  // fuctions used to enable or disable UART pins signal inversion
   bool setRxInvert(bool);
   bool setTxInvert(bool);
   bool setCtsInvert(bool);