Basilisk: Installing Optional Python Packages and Building Documentation

Provides an overview of the optional python packages that can be installed. Also discusses how to build the Basilisk documentation if you need the documentation of the latest develop branch, or you are writing new documentation that you want to test.

[liaokehengsite]

Since Basilisk is still a small but powerful simulation tool, I hope the official team will have more video introduction tutorials for different levels. We are using it!