Amended login required mixin documentation to honor **initkwargs.

docs/topics/class-based-views/intro.txt

@@ -189,8 +189,9 @@ mixin like this::
 
     class LoginRequiredMixin(object):
         @classmethod
-        def as_view(cls):
-            return login_required(super(LoginRequiredMixin, cls).as_view())
+        def as_view(cls, **initkwargs):
+            view = super(LoginRequiredMixin, cls).as_view(**initkwargs)
+            return login_required(view)
 
     class MyView(LoginRequiredMixin, ...):
         # this is a generic view