update readme

Author: Heliosmaster

README.md

@@ -1,6 +1,13 @@
 # SSH Auth Github
 
 This is a small [Babashka](https://github.com/borkdude/babashka/) script that retrieves public keys from a specific team under a specific organization on Github.
+This can be useful to essentially use GitHub teams as access control, making sure that only the people in a certain team
+have SSH access to machines. 
+
+This script can be used as `AuthorizedKeysCommand` or piped into `authorized_keys`.
+
+
+## Usage
 
 You need a `config.edn` next to the script with