python setup.py checkdocs (#376)

[chfw]

• 💚 check docs in setup.py

• 📚 fix readme

• ✨ add pygement packages to setup docs check

• 📚 update docs and release 0.7.3

Before raising the PR, here is a check list:

• have you written unit tests for your code changes?
• have you updated the change log?
• can someone else understand your changes without your explanation?
• are you proud of your code changes?
• please add your name and github link to contributors.rst in alphabetical order.