TODO: Add support for multifile binaries.

Hello

First I want to say: I think this project is a great idea. I like especially the fact that it makes it very easy to use simple plant-uml diagrams in the rust documentation.

I've seen your TODO

I think what I'm really looking forward could be the entry: "Add support for multifile binaries."

I have a main file surrounded by some other code files.

I just can't get documented more than the crate documentation for the main.rs Is this exactly what you mean by your TODO entry or is there another way to document also the other files?