Added code to allow compilation for esp8266

[Pius171]

I got an error when trying to compile for esp8266 so I simply added

#ifdef ESP32
#include <WiFi.h>
#elif defined(ESP8266)
#include <ESP8266WiFi.h>
#endif

The WiFi.h library is for esp32 so I simply added some code to allow it to use ESP8266WiFi.h when the board being used is an esp8266 board.

[rboeije1]

I noticed the issue when compiling one of the examples on an ESP8266. Inspecting the sourcecode, I noticed that the right wifi- and udp-flavor is now included from the library, but in the examples 'wifi.h' is still included. So that line should ideally be removed from the examples, and for convenience, make a note in the comments that including ezTime.h automatically includes wifi and udp.