README tweaks

Author: mxcl

README.md

@@ -6,6 +6,18 @@
 It mirrors the convenience of `npx` for the Cargo ecosystem while prioritising
 `cargo-binstall` to download prebuilt executables whenever possible.
 
+## Installation
+
+We recommend installing cargo-binstall as well, this significantly speeds up
+use of `cargox`:
+
+```sh
+cargo install cargo-binstall
+cargo binstall cargox-cli
+```
+
+If you don’t want that then you can just `cargo install cargox-cli`.
+
 ## Features
 
 - Executes `crate[@version]` binaries, installing them on demand.