Link to the extended Documentation is dead

## Dead Documentation Link
- Regarding [extended documentation](https://pydexpi.readthedocs.io/en/latest/)

- Error on Site https://pydexpi.readthedocs.io/en/latest/ :

 - "404 Project not found
The project you requested does not exist or may have been removed."

##  Suggested Fix 
- In `README.md` at **Line 89**
- Update Link