Add documentation

[Louis-Pujol]

Cleaned replay.py and add documentation about replay functionality

[akaszynski]

Made a few edits since the rendered RST bullets looked funky on GitHub (and probably would be on PyPI). This is good to go.

I've invited you to the repository and given you write access. You should have permission to merge once you've accepted the request.

[Louis-Pujol]

Thanks !