OneWireIO is not implemeted yet, state this in the Readme

[ilario]

When following the example from the Readme file, I get this error:

ow_bus = OneWireBus(pin.PB0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.9/dist-packages/adafruit_onewire/bus.py", line 69, in __init__
    self._ow = onewireio.OneWire(pin)
  File "/usr/local/lib/python3.9/dist-packages/onewireio.py", line 23, in __init__
    raise NotImplementedError("OneWire has not been implemented")
NotImplementedError: OneWire has not been implemented

This seems unavoidable, as OneWireBus calls OneWireIO here:

https://github.com/adafruit/Adafruit_CircuitPython_OneWire/blob/ecd884130f7a19def54cd2b720a7fd8b6f8c06c2/adafruit_onewire/bus.py#L69

And this happens since adafruit/Adafruit_CircuitPython_OneWire@692e01e

Then, OneWireIO will simply answer NotImplementedError:

https://github.com/adafruit/Adafruit_Blinka/blob/514f69e1d5d3ccdac2c414fad3344532671820d9/src/onewireio.py#L22-L23

So I consider that if this module cannot be used, this should be clearly stated in the Readme.

But I feel I am missing something... How did this work in the past? Seems that OneWire was not implemented neither in BusIO...