Covering new features for Rails 4

[Oscar Del Ben]

Hi guys,

I think it's time to make a plan for covering new features in the guides. I asked Santiago Pastorino on Twitter and he suggested the following, but there may be more:

* Russian doll caching

* Caches digest

* Etagger

* Strong parameters

* AC::Live

* Turbolinks

Please add more to the list.

Let's make a plan to cover these. I want to dedicate some time to writing but I need help figuring out the best way to present these features to the reader. Feel free to share your ideas.