Updated test documentation

Purpose

Updated the documentation to better reflect what tests we run and how to run them (See #52)

[x] My code follows the style of this project.
[x] The code compiles without warnings.
[x] I have performed a self-review of the changes.
[x] I have documented my code, in particular the intent of the hard-to-understand areas.
[x] (If necessary) I have updated the CHANGELOG.