We are going to deploy the new yiiframework.com website on March 23, 2018 from 8:00 to 12:00 UTC.
Website and Yii documentation will not be available in this time frame. Check the news for more details.
One of the common requests I see in the forum is how to implement RBAC. While you can implement Yii 2's built-in RBAC, that might be too much for developers who are just starting with Yii 2 or have simpler needs. Sometimes you are looking for a fast solution and just want two flavors, user and admin. And even if you will eventually need more, you can use these methods as a starting point for developing your own features or move on to Yii 2's RBAC.