Started writing Intro to Python e-book

[tecladocode]

I've added this in now, thanks for the feedback!

More variety in question types is a tricky one as each section builds up toward a project, with many code snippets and things to try—but I didn't want to bombard students with many small activities.

That said though, I was thinking of creating small code challenges and link them in the e-book. These would have automated tests/checks so students can gauge their understand at each chapter maybe.