The actual in-game manual will be similar to this online manual once the game is released.
At any time while playing Auro, you can browse the manual and read as much as you want. However, when things happen, you can always click on Quillsh to get more information about what he's saying, and it will take you to the relevant Manual page.
Here's a quick mockup of what 3 various Manual pages might look like (sans art):
Chapter 1 - The Basics
Chapter 2 - Special Abilities