update readme

Author: Hidenori MATSUKI

README.md

@@ -22,6 +22,10 @@ Options:
 
 1. Place the binary in your `$PATH`.
 
+```console
+curl -L https://github.com/mazgi/openssh-authorizedkeyscommand-github/releases/download/v0.0.1/openssh-authorizedkeyscommand-github.x86_64-unknown-linux-gnu.tar.gz | sudo tar xz -C /usr/local/bin/
+```
+
 2. Update `/etc/ssh/sshd_config`.
 
 ```ssh_config