Having the docs index in the repo root was a holdover from when it was
the README file. Now that it's not much use without being built, it's
better to leave the root to README, NEWS, and LICENSE - especially when
one is a html shortcut to the docs index.
The root of the documentation tree has a different function to the short
readme we want to display on GitHub, which now links to the main docs
(or Bay12 thread, or IRC). It also renders properly on GitHub, and can
use live-updating status badges because we don't expect it to work
offline.