feat(uart): add commentaties

Author: SuGlider

cores/esp32/HardwareSerial.h

@@ -357,6 +357,7 @@ class HardwareSerial : public Stream {
   void setDebugOutput(bool);
 
   // fuctions used to enable or disable UART pins signal inversion
+  // returns the requested operation success status
   bool setRxInvert(bool);
   bool setTxInvert(bool);
   bool setCtsInvert(bool);