Update README (rust-lang#464)

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

README.md

@@ -15,7 +15,8 @@ You probably want to **[see this page as it was when the latest version was publ
 
 ## Installation
 
-To get started _using_ `cargo-binstall` first install the binary (either via `cargo install cargo-binstall` or by downloading a pre-compiled [release](https://github.com/cargo-bins/cargo-binstall/releases)). We recommend using the pre-compiled ones because we optimize those more than a standard source build does.
+To get started _using_ `cargo-binstall` first install the binary (either via `cargo install cargo-binstall` or by downloading a pre-compiled [release](https://github.com/cargo-bins/cargo-binstall/releases)), then extract it using `tar` or `unzip` and move it into `$HOME/.cargo/bin`.
+We recommend using the pre-compiled ones because we optimize those more than a standard source build does.
 
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