esp32/README: Update general description of port to add avail features.
esp32/README: Update general description of port to add avail features.

micropython/micropython-esp32,MrSurly/micropython-esp32,micropython/micropython-esp32,MrSurly/micropython-esp32,MrSurly/micropython-esp32,MrSurly/micropython-esp32,micropython/micropython-esp32,MrSurly/micropython-esp32,micropython/micropython-esp32,micropython/micropython-esp32