Doc - Describe `cairo_run` using Rustdoc comments (three slashes: ///)

[Eikix]

In an effort of having fully documented code, we need our cairo runner to be documented.

Please proceed to comment above the pub fn cairo_run declaration in an equivalent way as pub fn compile is documented.

[ptisserand]

Hi, can I work on this issue?

[Eikix]

Sure thing!