updated read me

Author: Christian Hansen

Readme.md

@@ -2,7 +2,9 @@ Simple OAuth 2.0
 
 Currently setup for Google API (Gmail, Google+ etc.) but should work for other OAuth 2.0 services.
 
-1. Register and app here: https://code.google.com/apis/console/ (or other OAuth 2.0 service)
+1.A Register and app here: https://code.google.com/apis/console/ (or other OAuth 2.0 service) 
+
+1.B For Google API be sure to register the Platform as "Other" and NOT "iOS" otherwise you'll get "invalid_client" error when authenticating.
 
 2. Insert your Client ID and Client Secret in ViewController.m (and optionally change the authentication-url and token-url if you're not using Google API)