Add python 3 tutorial

[sugarsyntax]

I don't know if you guys have already heard of this resources progate.com, it's similar to codecademy, one major difference is their python course is python 3 and free, unlike codecademy. https://progate.com/languages/python

[capsulecorplab]

Looks good! I'd probably add a link to the home website itself and list all the languages it offers in the description.