In terms of content, they seem to be on par, and I think it's safe to say that's true for both stdlibs.

Across the ecosystem (and particularly the third-party culture of documentation) is much more important; in my own experience playing with both languages, I tended to encounter more useless 1-line descriptions in golang than I did in Rust.

Also golang struct descriptions always seem to be a bit lackluster..

But I can't point to any particular lib at the moment though.