Small update to satisfy stricter checks of Arduino IDE's compiler

(no functional change)

Implemented class B control

The lib should now support QC class B chargers and powerbanks, up to 20V.
Fix to getVoltage(), getMilliVoltage() and misc doc updates

Fixed outdated code

v1.2.0 somehow included old code which required 3 pins. Fixed.
Details were also updated in the doc

Re-packed with correct version in library.properties

v1.2.0

Updated version to 1.2