message: readme: add link to the cargo documentation on docs.rs
diff: @@ -9,6 +9,8 @@ Learn more at https://doc.rust-lang.org/cargo/
  [![Build Status](https://travis-ci.org/rust-lang/cargo.svg?branch=master)](https://travis-ci.org/rust-lang/cargo)
  [![Build Status](https://ci.appveyor.com/api/projects/status/github/rust-lang/cargo?branch=master&svg=true)](https://ci.appveyor.com/project/rust-lang-libs/cargo)
  +Code documentation: https://docs.rs/cargo/
  +
  ## Installing Cargo
  Cargo is distributed by default with Rust, so if you've got `rustc` installed
  