Adafruit-circuitpython-pcf8574

Fixed the circup installation instructions in the README. Thanks FoamyGuy!

To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-pcf8574`.

Read the [docs](https://circuitpython.readthedocs.io/projects/pcf8574/en/latest/) for info on how to use it.

Changes: https://github.com/adafruit/Adafruit_CircuitPython_PCF8574/compare/1.0.7...1.0.8

To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-pcf8574`.

Read the [docs](https://circuitpython.readthedocs.io/projects/pcf8574/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-pcf8574`.

Read the [docs](https://circuitpython.readthedocs.io/projects/adafruit-circuitpython-pcf8574/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-PCF8574`.

Read the [docs](http://circuitpython.readthedocs.io/projects/PCF8574/en/latest/) for info on how to use it.

Added type annotations to this library. Thanks tcfranks!

To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-pcf8574`.

Read the [docs](http://circuitpython.readthedocs.io/projects/pcf8574/en/latest/) for info on how to use it.

To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-pcf8574`.

Read the [docs](http://circuitpython.readthedocs.io/projects/pcf8574/en/latest/) for info on how to use it.