If you install this extension, a lot of changes will happen to your TYPO3 backend. Thus you should take care to install it only in a development environment, as you may otherwise run into some surprises.
In various parts of the code contained in this extension, you will find PHP comments that look like this:
// USAGE: TCA Reference > Additional $TCA features
This points to which manual (and which part of the manual) refers to the given code sample. This will help you find where to find the related explanations.