Documentation for existing components/features

[calummackervoy]

My suggestion:

• set up a GitHub pages site for this repository
• set up minimal documentation on the existing components/features exported by the library

[MattTennison]

There's https://storybook.js.org/ but it's very much focused on UI components and doesn't really have a good way of introducing the library as a whole.

MDX is a pretty neat (lets you use Markdown to write JSX) format, we could incorporate that into something custom using Gatsby but it could be time consuming to setup.

There's also https://docusaurus.io/ which, after a two minute scan through their website, seems to just let us write MDX files and it does all the heavy lifting.

[MattTennison]

The more I look at docusarus, the better it looks. Covers a bunch of key features that'd be a faff to write ourselves like searching, versioning and claims to be SEO-friendly. It's also being used by big projects like Jest so it might look and feel familiar to new developers.

Seems like the right choice for this stage in the project.