update README

privatebin/README.md

@@ -5,6 +5,8 @@ Paste securely.
 #### Features
 - Based on Alpine Linux (hoellen/nginx-php image)
 - Uses [PrivateBin](https://github.com/PrivateBin/PrivateBin), originally a fork of zerobin by elrido.
+- GPG signature check
+- separate /data directory
 - Bundled with nginx and PHP7.2
 
 #### Build-time variables