wrong README.md

### Step 2: Describe the problem:

If you follow the instructions in the README.md

4. Copy public key and in index.html file replace with your key.

there is no index.html in console.firebase.google.com/..../cloudmessaging
and if you want to "learn more" it ends up in this https://developers.google.com/web/updates/2016/07/web-push-interop-wins#introducing_vapid_for_server_identification
[Service Unavailable]

where can I learn more?

thanks
s.