add readme with links

This is a repo where I put ideas for UI components for the eleventy-plugin-repoviewer default template. I'm using the buildSteps feature of repoviewer to put the resulting HTML pages on the web.

So far, those are:

- [index.html](demo/index.html)
- [index-slim.html](index-slim/index.html)
- [index2.html](demo/index2.html)
- [main-slim.html](demo/main-slim.html)
- [index2.html](demo/index2.html)