docs: Several corrections to the classes in the machine module.

docs/library/machine.HeartBeat.rst

docs/library/machine.Pin.rst

docs/library/machine.SD.rst

docs/library/machine.Timer.rst

docs/library/machine.UART.rst

docs/library/machine.WDT.rst

docs/library/machine.rst

docs/library/network.rst

docs/library/ussl.rst

docs/wipy/general.rst

docs/wipy/quickref.rst