Add a note about recent features to pre-eject message

[gaearon]

When we ask:

>Are you sure you want to eject? This action is permanent.

we should also mention that features like CSS Modules, Sass, TypeScript, and others are supported without ejecting. Judging by the eject survey responses many people don't realize this.

Shouldn't sell too hard. Just needs to mention them and link to 2.0 blog post.