Add benefits

[ShalokShalom]

This adds an overview for the cpp2 benefits.

I really liked one of Herb's comment on Reddit, as it provided a very nice overview about the benefits of this project.

This commit adds that comment in slightly different form, and I hope it can lead to a better understanding of the benefits of Cpp2.

I feel like the current README misses a short, condensed overview, for what cpp2 already achieves today.

In some talks with existing cpp developers, I found that their subjective interpretation of the state of the language is FAR behind the reality.