* Addition: Shutdown time setting
* Add a function to change the time setting register
* Add maximum time (64s) setting at initialization
(If you prefer short time settings, set them yourself after initialization)
* Add : powerOFF function
* Fix : Adjusted function name
*setLowCurrentShutdownTime -> setLowPowerShutdownTime
*SleepTime -> ShutdownTime
*SLEEP_xxS -> SHUTDOWN_xxS
Add : powerOFF function
* fix:Detailed setting of wakeup factor
If you set the wakeup time, it will be reflected incorrectly even when it is not needed.
* modify : Exclude functions that don't work properly
*setLowPowerShutdown() -> Add attribute
*setKeepLightLoad() -> Add attribute
* add : add Link
*Add a reference to the official document
* Modify sleep.ino comment