Added link to new RBAC page

docs/guide/index.md

@@ -56,7 +56,7 @@ Security and access control
 - [Authorization](authorization.md) - Access control and RBAC
 - [Security](security.md) - Hashing and verifying passwords, encryption
 - [Views security](view.md#security) - how to prevent XSS
-- Role based access control
+- [RBAC](rbac.md) - Role-based Access Control
 
 Data providers, lists and grids
 ===============================
@@ -84,4 +84,4 @@ References
 ==========
 
 - [Model validation reference](validation.md)
-- [Official Composer documentation](http://getcomposer.org)
+- [Official Composer documentation](http://getcomposer.org)