add docs link to readme

Author: FoamyGuy

README.rst

@@ -75,11 +75,16 @@ Usage Example
         pin1.value = False
         time.sleep(1)
 
+Documentation
+=============
+
+API documentation for this library can be found on `Read the Docs <https://circuitpython.readthedocs.io/projects/74hc595/en/latest/>`_.
+
 Contributing
 ============
 
 Contributions are welcome! Please read our `Code of Conduct
-<https://github.com/adafruit/Adafruit_CircuitPython_74HC595/blob/main/CODE_OF_CONDUCT.md>`_
+<https://github.com/adafruit/Adafruit_CircuitPython_74HC595/blob/master/CODE_OF_CONDUCT.md>`_
 before contributing to help this project stay welcoming.
 
 Documentation