Add `ready` event to readme example

Hey guys!

I've fixed a couple of issues with the readme:

1. I've added the `ready` event to the example code. This one tripped me up when I implemented `moonboots` for a side project!
2. I also fixed a small typo with the word "synchronously". To be honest, I can't spell that word 50% of the time.

Thanks for everything that you are doing!