While others are pointing you towards library docs I highly suggest going to the rust book[1] instead. A lot of languages you are fine learning breadth first by going through some documentation and playing around building things. This is how I learn best myself, but it doesn't work well with rust. It has enough unique concepts and concepts you might not have come across unless you have experience with a similar language. It is one language that is best served by a depth first approach. I usually suggest reading chapters 1-11 before trying to dive in and build something.

1. https://doc.rust-lang.org/book/index.html

Sort of. Rust's Standard Library documentation describes the entire language in perhaps the way you're thinking of

https://doc.rust-lang.org/std/index.html

e.g https://doc.rust-lang.org/std/keyword.as.html explains the 'as' keyword

https://doc.rust-lang.org/std/primitive.i128.html documents the 128-bit signed integer type

Or, maybe you are thinking purely a language document like:

https://doc.rust-lang.org/reference/introduction.html

https://doc.rust-lang.org/std/index.html has the documentation for the standard library.

In addition https://docs.rs contains the documentation for all publicly available Rust code.

The main tool used to generate these docs is very good and easy to use. As a result documentation is usually pretty good.