Merge #20

20: move doc comments inside macro invocations r=Disasm a=euclio

[rust-lang/rust#57882](https://github.com/rust-lang/rust/pull/57882

) is modifying the `unused_doc_comments` lint to fire on mistakenly documented macro expansions. Note that these doc comments are not currently used, since they are eliminated when the macro is expanded. A crater run detected that this crate will break due to this change, likely because of the use of `deny(unused_doc_comments)` or `deny(warnings)`.

While this kind of breakage is allowed under Rust's stability guarantees, I am opening PRs to affected crates to reduce the impact.

This PR protects your crate from future breakage by moving the offending doc comments inside the macro invocations.

Co-authored-by: Andy Russell <arussell123@gmail.com>