Remove mention of `convert_key` now that it's been taken out in...

Remove mention of `convert_key` now that it's been taken out in 1eecd948

activesupport/lib/active_support/core_ext/hash/except.rb

@@ -4,13 +4,6 @@ class Hash
   #
   #   @person.update_attributes(params[:person].except(:admin))
   #
-  # If the receiver responds to +convert_key+, the method is called on each of the
-  # arguments. This allows +except+ to play nice with hashes with indifferent access
-  # for instance:
-  #
-  #   {:a => 1}.with_indifferent_access.except(:a)  # => {}
-  #   {:a => 1}.with_indifferent_access.except('a') # => {}
-  #
   def except(*keys)
     dup.except!(*keys)
   end