One of the feature I like the most on Rust is automatic documentation. Documentation is a pillar in language ergonomic, and I love that Rust spend so much time into making documentation and documenting code a much pleasant experience.

Rust autogenerated documentation (with cargo doc) looks good, every crate on crates.io get its documentation published on docs.rs, and, most important, every code example in the code is compiled and run as a “unit test” making sure that all the examples are up-to date!