Help Needed with Documentation

On the folder stucture, the downloaded installation does not have the tests directory either.

However, on the Extending the Controllers questions, there are 2 ways of doing it. Either extending the CodeIgniter System Controller Directly or more preferably extending the BaseController in you app folder. 

This part is documented in : https://codeigniter.com/user_guide/exten...controller

However, a reference to this section can be added into the First Application for clarity.