Add README to demos folder

[mmkal]

There's a demos folder, with lots of useful-looking html, but I'm unsure how we're supposed to view it? I've tried cloning and simply opening the html files, but am getting

assets/material-components-web.css.js Failed to load resource: net::ERR_FILE_NOT_FOUND

There's no .md file in the demos folder, no assets folder anywhere I could find, and no package.json so running npm install doesn't do much. Is it explained anywhere how to actually view these demos?

[amsheehan]

This is something we should address. In the mean time you can read the instructions on running the demo here

TL;DR: After installing everything, run: npm run dev

[mmkal]

Got it, thanks - that works for me for now. I won't close this since it looks like you may plan to add some docs to the demos folder, but if that's tracked somewhere else feel free to close for me.

[traviskaufman]

Agreed that we should put a basic README in the demos folder. Changing the issue title and adding to tracker.