Updated README information regarding the pre_user_save signal handler.

Author: Dan Campbell

README.rst

@@ -415,12 +415,12 @@ following code to your app::
 
   from djangosaml2.signals import pre_user_save
 
-  def custom_update_user(sender=user, attributes=attributes, user_modified=user_modified)
+  def custom_update_user(sender=User, instance, attributes, user_modified, **kargs)
      ...
      return True  # I modified the user object
 
 
-Your handler will receive the user object, the list of SAML attributes
+Your handler will receive the user object instance, the list of SAML attributes
 and a flag telling you if the user is already modified and need
 to be saved after your handler is executed. If your handler
 modifies the user object it should return True. Otherwise it should