That seems like a great idea in principle, but for most small projects the GitHub page /is/ the documentation. If that weren't the case, you wouldn't see half a dozen links to GitHub pages to show off projects on HN each day.
It's all very well to talk about ideals, but you can't ignore reality in the process.
You're right, though, that you shouldn't have to scroll past it every time. I don't really know what the solution is, but having it there but going undiscovered is the worst of both worlds.
