Library ignores if EERPROM is already being used

[AussieMakerGeek]

Hi - This one took me ages to figure why my existing code that uses the EEPROM broke as soon as I enabled the cache on ezTime.

Looking at line 878 of ezTime.cpp I see that once it has written to the EEPROM, it issues an eeprom.end() command when using ESP32.

Perhaps document this as well as maybe adding the option to disable this (Why end it anyway?).

I'm a bit fresh to the ESP32 and this code was migrated from Arduino Uno from some time ago so I have not messed with the NVS stuff yet - it's probably a better way to go but once the values in my device are set, they will stay for a long time.

Thanks for the great work.