Document UI guides (design systems, packages we use)

[kellective]

I'm working to document where we want to be moving to with the Storybook library, how we use styled-components, how we want to move towards consistency with icons, colours, type.

We will have the details of the designs inside the documentation of story book but this documentation here will outline our plan, packages, processes and current state.

Currently the documentation addon to Storybook breaks with our setup (typescript thing probably).