Complete a sentence in i18n guide's introduction

Add a list of what will be covered into this guide

guides/source/i18n.md

@@ -21,6 +21,11 @@ This guide will walk you through the I18n API and contains a tutorial on how to
 
 After reading this guide, you will know:
 
+* How I18n works in Ruby on Rails
+* How to correctly use I18n into a RESTful application in various ways
+* How to use I18n to translate ActiveRecord errors or ActionMailer E-mail subjects
+* Some other tools to go further with the translation process of your application
+
 --------------------------------------------------------------------------------
 
 NOTE: The Ruby I18n framework provides you with all necessary means for internationalization/localization of your Rails application. You may, however, use any of various plugins and extensions available, which add additional functionality or features. See the Rails [I18n Wiki](http://rails-i18n.org/wiki) for more information.