Add txt2tags plugin to list in repo ReadMe

Readme.rst

@@ -242,6 +242,8 @@ Touch                     Does a touch on your generated files using the date me
 
 Twitter Bootstrap         Defines some rst directive that enable a clean usage of the twitter bootstrap CSS and Javascript components
 
+txt2tags_reader           Reader that renders txt2tags markup in content
+
 W3C validate              Submits generated HTML content to the W3C Markup Validation Service
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