Add a detail description of Whales micro-service architecture on "Why" section

[mayra-cabrera]

On README we have a small section titled "Why?". The purpose of this section is to explain what is the Whales ecosystem, and how does it work.

The how does it work part is missing, any ideas of how we can explain it, in a way that is interesting and compelling?

Maybe a drawing of the architecture?

Thoughts? @vovimayhem @kurenn @thelastinuit