Docusaurus site to break up the README?

[cspotcode]

@blakeembrey how do you feel about having a Docusaurus site for ts-node, letting us break up the README into multiple pages? Motivation is to improve the appeal and discoverability of the information in our README, since it's a bit long.

I've used Docusaurus at work, and it's the simplest way I know to render markdown into an attractive docs site. You create docs/*.md files and each is rendered as a page. It'll be easy to setup on Github Actions. It could live at https://TypeStrong.github.io/ts-node

On the other hand, I don't like that the npmjs.com README will be different than the documentation site. We'd either have to make the readme empty, or somehow duplicate high-profile documentation between the docs site and the README. Or some smart copy-pasting script to keep them in sync? None of those ideas sound good.

Alternatively, maybe we add a table of contents to the README with http://npm.im/markdown-toc?

[cspotcode]

Initial implementation is merged; will keep iterating on the pages till it's ready to be "official."