Contribute to docs/tests?

[Ralph]

Documentation improvements

I just went through a huge proofread and update of the docs of fastai and there are quite a few of them that could be improved. [need_you] If you’re looking to help a bit with fast.ai while learning a little bit more about how the library works before part 2 of the course, this is a very good thing to look into. All the functions are properly documented but in some cases, we’re seriously lacking some examples (sometimes a lot of them). it doesn’t need to be super-evolved, but just a little exa…