Add usage example to README.md

[mb720]

Here's a small usage example that I would loved to see available when I started using wayvnc.

[lack]

I like the sentiment of this patch, but I think there are 2 things that would make it better:

• Move it into FAQ.md
• If you're setting up ssh anyway, it's much safer to tunnel your VNC traffic through SSH using ssh -L 5900:localhost:5900 $user@$host wayvnc, and then connect your client to localhost:5900