[ESP32] How to reset based upon command from serial

[Idahowalker]

@StefanL38

Of course an ESP32 has more RAM than an Arduino-Uno. But it is just a matter time until the RAM-overwrite caused through repeated assigning new content to the string-variable happends.

Unless, of course, one properly uses the ESP32's built in OS, freeRTOS. freeRTOS will clean up those pesky String caused memory holes.