You can use this documentation in two ways, or just as a reference or for learning.
It is devided in difficulty levels from user to developer, you can start reading and stop when it is no longer of your interest.
Just show me how to use the grid without going into its internals.
I want a better understanding about the grid internals, I want to customize the grid settings to my needs and take advantage of some internal functionality.
Lets get dirty into the code, understand, change and extend the grid functionalities.