docs/esp8266: Add note about simultaneous use of STA_IF and AP_IF.
docs/esp8266: Add note about simultaneous use of STA_IF and AP_IF.

See also https://github.com/esp8266/Arduino/issues/1624

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython