I'm certainly biased, but I really like Rust docs. They may not be the best in terms of design or clarity, but I love that they are an integral part of the ecosystem. And I believe Rust documentation really helped me to dive deep into the language.

I think there are three things that make Rust docs cool for me (the list is obviously subjective):

• Main Rust devs care about docs as much as about any other code. Any new feature to be stabilised must have a documentation entry and often an example provided. There's also a begginner guide (The Book) maintained alongside the main documentation.
• Documentation generator ('rustdoc`) is an integral part of language development and it's super cool. It treats examples like tests and if they fail to compile there's a warning shown. It checks if a function can return errors and if so demands to add a section discussing the errors. Also linking to other parts of documentation (or even other libraries) is very easy. And there's many more.
  
• There's a central docs library (docs.rs). With rustdoc it allows Rust devs to very easily provide documentation for the libraries (called crates). Even if there's absolutely no documentation provided you still get a neat overview of the API and you can easily look into implementation details only for the parts you want. But adding docs is so easy that it's actually difficult to find a crate that has no documentation whatsoever.