Adding CMS sections

README.md

 * [Knp RAD Components](https://rad.knplabs.com/) - A set of Rapid Application Development (RAD) components for Symfony.
 * [Symfony CMF](https://github.com/symfony-cmf/symfony-cmf) - A Content Management Framework to create custom CMS.
 
-### Components
+## Content Management Systems (CMS)
+* [Drupal](https://www.drupal.org) - Enterprise Level Content Management System.
+* [WordPress](https://wordpress.org/) Blogging platform and Content Management System.
+* [Joomla](https://www.joomla.org/) - Another lead Content Managemenet System.
+* [Concrete5](http://www.concrete5.org/) - A Content Management System targering users with a minimum of technical skills.
+* [BackdropCMS](https://backdropcms.org/) - a fork of Drupal; it's a Content Management System for the non-profits and small-to-medium.
+
+## Components
 *Standalone components from web development frameworks and development groups.*
 
 * [Aura](http://auraphp.com/) - Independent components, fully decoupled from each other and from any framework.