Set-up documentation styling & layout

[ruiconti]

Issue

We need to have a typograpic and aesthetic face! 😎

Proposed solution

Get help from our product staff + help of some very talented frontend engineers (cc @marianaks @phenrique7 @diogomqbm).

This task is blocked by #12, as we should already have a doc environment in order to customize it (Duh right)