RBAC documentation

docs/guide/rbac.md

+What is Yii
+===========
+
+Yii is a high-performance, component-based PHP framework for rapidly developing large-scale Web applications. Yii enables maximum reusability in Web
+programming and can significantly accelerate your Web application development
+process. The name Yii (pronounced `Yee` or `[ji:]`) is an acronym for
+**Yes It Is!**.
+
+
+Requirements
+------------
+
+To run a Yii-powered Web application, you need a Web server that supports
+PHP 5.4.0 or greater.
+
+For developers who want to use Yii, understanding object-oriented
+programming (OOP) is very helpful, because Yii is a pure OOP framework.
+Yii 2.0 also makes use of the latest features of PHP such as [namespaces](http://www.php.net/manual/en/language.namespaces.php)
+so you should be familiar with how they work.
+
+
+What is Yii Best for?
+---------------------
+
+Yii is a generic Web programming framework that can be used for developing
+virtually any type of Web application. Because it is light-weight and
+equipped with sophisticated caching mechanisms, it is especially suited
+to high-traffic applications, such as portals, forums, content
+management systems (CMS), e-commerce projects, etc.
+
+
+How does Yii Compare with Other Frameworks?
+-------------------------------------------
+
+- Like most PHP frameworks, Yii is uses the MVC (Model-View-Controller) design approach.
+- Yii is a fullstack framework providing many solutions and components, such as logging, session management, caching etc.
+- Yii strikes a good balance between simplicity and features.
+- Syntax and overall development usability are taken seriously by the Yii development team.
+- Performance is one of the key goals for the Yii framework.
+- The Yii development team is constantly watching what other Web frameworks are doing to see what best practices and
+  features should be incorporated into Yii. The initial Yii release was heavily influenced by Ruby on Rails.
+  Still, no framework or feature is being blindly copied into Yii; all decisions are based upon what's best
+  for Web developers and in keeping with Yii's philosophy.