That may sound like a contradiction, since Propel is classically used by developers on computers, but you don't need to be in front of your desktop or laptop to learn Propel.
This is because the Propel website is now optimized for smartphones and tablets. Just browse to http://www.propelorm.org with your mobile device, and enjoy the complete Propel documentation in a readable form.
I don't know about you, but I often need to check some Propel implementation details, or to show some code examples, while not in front of a computer. Now it's possible!
Found a typo ? Something is wrong in this documentation ? Just fork and edit it !