README.md.erb in twoffein-client-0.1.1 vs README.md.erb in twoffein-client-0.1.2

@@ -21,9 +21,16 @@
 
 ```
 <%= %x[bundle exec bin/twoffein-client --help] %>
 ```
 
+### Credentials
+
+You need your credentials (screen_name, api_key) to get access to the Twoffein-API. Please set these as
+shell environment variables `TWOFFEIN_SCREEN_NAME` and `TWOFFEIN_API_KEY`. Thank's!
+
+    TWOFFEIN_SCREEN_NAME=NAME TWOFFEIN_API_KEY=KEY twoffein-client drinks
+
 ## Examples
 <%
     def self.example(title, command);
         title = "### #{title}"
         input = "**Input:**\n\n    #{command.gsub("bundle exec bin/",'')}"