Docs: switch to storybook

[paibamboo]

Styleguidist use .md file as a documentation which is somewhat nice. But these docs get old pretty quickly when people add or remove props to/from a component. Build should fail if docs are not up-to-date, but we can't enforce that using Styleguidist.

At the time Storybook didn't have as many flexibilities as it does now. If I recalled correctly, we needed to combine doc in one file, we couldn't have one doc per one component. Also we couldn't add descriptions to the doc, and we couldn't generate component props table from typescript interface, we couldn't even show source codes of the rendered component. But now we can do all of these, so it makes sense to switch to Storybook.