[Rust] Remove redundant documentation

[seritools]

Ok() and disassembly text on success, Err() otherwise. is implied by using Result, so it only really increases noise when looking through the documentation.

In general, I don't see a single # Returns block that is not redundant with the function signature in the public Rust API.

[pkoppe]

Agreed, it's a little verbose, at the same time it's not hurting the docs. We keep the comments as is for now.