Use rustdocs new intra-doc feature

[rusty-snake]

trafficstars

Rustdoc has a new feature which resolves links to other types,methods,... in doc-comments. This prevents 404 links and other trouble. Let's use it everywhere :rocket: .

https://blog.rust-lang.org/2020/11/19/Rust-1.48.html#easier-linking-in-rustdoc https://doc.rust-lang.org/rustdoc/linking-to-items-by-name.html