update docs to mention disabling ad blocker
I got this issue when first loading the demo:

```
bradoyler.github.io/:7 GET https://authedmine.com/lib/authedmine.min.js net::ERR_BLOCKED_BY_CLIENT
main.js:8 Uncaught ReferenceError: CoinHive is not defined
    at Object.<anonymous> (main.js:8)
    at e (bootstrap 861f4ece923278967c50:19)
    at bootstrap 861f4ece923278967c50:62
    at bootstrap 861f4ece923278967c50:62
```

It wasn't obvious but I needed to turn off my ad blocker. Maybe mention in the README about ad blockers?