Update README.md

test/taiko/ptf-demo/README.md

@@ -5,6 +5,10 @@
     npm install -g taiko-screencast taiko
     sudo apt install ffmpeg
 
+    export DOMAIN='oas.example.org'
+    export SSO_USERNAME='taiko-tmp'
+    export SSO_USER_PW='...'
+
 ## Usage
 
     taiko --observe ptf-demo.js