update docs before_validation_on_create => before_validation(:on => :create)

activerecord/lib/active_record/callbacks.rb

@@ -31,7 +31,7 @@ module ActiveRecord
   #   class CreditCard < ActiveRecord::Base
   #     # Strip everything but digits, so the user can specify "555 234 34" or
   #     # "5552-3434" or both will mean "55523434"
-  #     def before_validation_on_create
+  #     before_validation(:on => :create) do
   #       self.number = number.gsub(/[^0-9]/, "") if attribute_present?("number")
   #     end
   #   end