Adjust README section for serializers to show full namespace of built…

…-in modules [ci skip]

README.md

@@ -913,8 +913,8 @@ By default, PaperTrail stores your changes as a `YAML` dump. You can override th
 
 A valid serializer is a `module` (or `class`) that defines a `load` and `dump` method.  These serializers are included in the gem for your convenience:
 
-* [YAML](https://github.com/airblade/paper_trail/blob/master/lib/paper_trail/serializers/yaml.rb) - Default
-* [JSON](https://github.com/airblade/paper_trail/blob/master/lib/paper_trail/serializers/json.rb)
+* [PaperTrail::Serializers::YAML](https://github.com/airblade/paper_trail/blob/master/lib/paper_trail/serializers/yaml.rb) - Default
+* [PaperTrail::Serializers::JSON](https://github.com/airblade/paper_trail/blob/master/lib/paper_trail/serializers/json.rb)
 
 ## Limiting the number of versions created per object instance