Added short section for AX data requests

README

@@ -214,5 +214,18 @@ You can support it in your app by changing #open_id_authentication
         { :login => 'nickname', :email => 'email', :display_name => 'fullname' }
       end
 
+Attribute Exchange OpenID Extension
+===================================
+
+Some OpenID providers also support the OpenID AX (attribute exchange) protocol for exchanging identity information between endpoints.  See more: http://openid.net/specs/openid-attribute-exchange-1_0.html
+
+Accessing AX data is very similar to the Simple Registration process, described above -- just add the URI identifier for the AX field to your :optional or :required parameters.  For example:
+
+        authenticate_with_open_id(identity_url, 
+            :required => [ :email, 'http://schema.openid.net/birthDate' ]) do |result, identity_url, registration|
+
+This would provide the sreg data for :email, and the AX data for 'http://schema.openid.net/birthDate'
+
+
 
 Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license