The Rust module system for Python users

[arxanas]

https://blog.waleedkhan.name/rust-modules-for-python-users/

[monocasa]

It should probably mention the special cased mod.rs files.

[arxanas → monocasa]

I didn't mention it since the intention of these notes is to aid in writing new Rust 2018 code. So far, I haven't had to know the details of mod.rs to use any third-party libraries.

[monocasa → arxanas]

You don't need it to use libraries, but it aids heavily in reading other rust code which is probably the best way to understand rust idioms.