I think what is missing is the explanation of a subscription. On the github-page, there is only one sentence in that regard:

> REST Hooks are a lightweight subscription layer on top of your existing REST API.

That is too short. There the explanation is missing, the same way on the website. maybe in better english if mine is broken, but that addition could fix it: "...,thus that instead of having to poll that API regularly, the subscriber is notified with a POST the moment a change occurs."

I'm probably biased, because that is kind of the same way I once tried to explain the concept, but I think it would be clearer that way.