"I think it might be a *little* misleading to say you don't have to maintain or read *any* documentation, or that there's *no* out-of-band information between server & client.
As you quoted, along with the initial URI, you do need to describe & document the "set of standardized media types that are appropriate for the intended audience". In fact, this very post works to explain approaches to building an aspect of those media types (ie. linking).
So, you still need docs. But, it's just that the thing to document are the media types. This is a shift from presenting exhaustive lists of remote methods or URLs.
It's also enough of a brain-tweaking shift that it's also handy to offer tutorials or at least example sequences of HTTP activity to show how to traverse from one resource to another using your media types. Being able to browse through the API by following links is handy, but how to get things done practically can sometimes be non-obvious at first."