message: Make it clearer that rustup will also install cargo
  Make it clearer that cargo is automatically installed when installing Rust using `rustup`.
diff: ### Install Rust and Cargo
  The easiest way to get Cargo is to install the current stable release of [Rust]
  -by using `rustup`.
  +by using `rustup`. Installing Rust using `rustup` will also install `cargo`.
  On Linux and macOS systems, this is done as follows:
  