chore(docs): setup automatic documentation

[UrbanoFonseca]

Features:

• Automatic documentation of docstrings
• Adhoc documentation of rst files
• Custom CSS formatting by defining the /docs/_static/css/custom.css file

To build the documentation

pip install -e .
pip install -r requirements-dev.txt
cd docs
make clean && make html
xdg-open _build/html/index.html