New documentation

[adamkudrna]

Current documentation is very basic. It consists of:

1. Foundation showcase (colors, typography, icons, spacing, breakpoints)
2. Layout components showcase
3. UI components showcase
4. Screens showcase
5. Utility classes showcase

Problems:

• Developers find the docs hard to use because it doesn't contain important information like code examples or description of components' API.
• It is very difficult to maintain since it's held in a single file.
• Designers (and actually no one except contributors) cannot browse the docs because it's not served anywhere in public.

Proposal:

• Find a way to split the docs into multiple files and screens to improve maintainability and navigation in browser.
• Provide components with code examples to help developers use the components.
• Provide components with API description to help developers use the components. This could be generated from propTypes comments.
• Consider using external tools like Storybook as it solves many of the problems.
• Serve the docs as a website to encourage designers use the UI library and to make it accessible to public.

Individual issues are expected to be raised as discussion continues within this issue.

[adamkudrna]

https://whoisryosuke.com/blog/2018/automating-react-documentation-using-react-docgen/

[adamkudrna]

Serve the docs as a website to encourage designers use the UI library and to make it accessible to public.

Moved to #67.