Update 4_0_release_notes.md

Active support --> Deprecations Code highlighted.

guides/source/4_0_release_notes.md

@@ -190,13 +190,13 @@ Please refer to the [Changelog](https://github.com/rails/rails/blob/master/activ
 
 * Deprecate `ActiveSupport::TestCase#pending` method, use `skip` from MiniTest instead.
 
-* ActiveSupport::Benchmarkable#silence has been deprecated due to its lack of thread safety. It will be removed without replacement in Rails 4.1.
+* `ActiveSupport::Benchmarkable#silence` has been deprecated due to its lack of thread safety. It will be removed without replacement in Rails 4.1.
 
 * `ActiveSupport::JSON::Variable` is deprecated. Define your own `#as_json` and `#encode_json` methods for custom JSON string literals.
 
-* Deprecates the compatibility method Module#local_constant_names, use Module#local_constants instead (which returns symbols).
+* Deprecates the compatibility method `Module#local_constant_names`, use `Module#local_constants` instead (which returns symbols).
 
-* BufferedLogger is deprecated. Use ActiveSupport::Logger, or the logger from Ruby standard library.
+* `BufferedLogger` is deprecated. Use `ActiveSupport::Logger`, or the logger from Ruby standard library.
 
 * Deprecate `assert_present` and `assert_blank` in favor of `assert object.blank?` and `assert object.present?`