Split the Python Introduction chapter to use files instead of command line

[olasitarska]

When it comes to loops and conditionals, typing it in a command line interface starts to be a pain.

[phalt]

What text editor is best at this point? Nano? Do we want to shift things around to recommend the code editor pages first?

[olasitarska]

I think Nano is confusing, we should use the editor that will be used later in the workshop, so I vote for moving Code editor chapter earlier than the Python Introduction.

If you want to work on this, @bmispelon had some good ideas in #207 too.

[olasitarska]

Btw, order of chapters is in SUMMARY.md file :)

[phalt]

Gotcha

[bmispelon]

Fixed in 73c5d6b.

Thanks to all those involved!