Unlike many other languages, Ruby doesn't have great design for documentation. Perl has "perldoc" feature and users easily access documents of modules by "perldoc" command. Python has "docstring" feature and users can access it on REPL. Those are each language's design of importance. The features are not just tool, it contains toolchains and eco-systems. Users of these languages benefit from good documentation design, so library authors write good documentation for them.
I'll talk about new Ruby 3's standard documentation design. It pretty improves your development experience.