Presently the index page of the documentation makes no attempt to
clarify what Moonraker is or even that it has anything to do with 3D
printing or CNC machine control. This attempts to add a basic
clarification by using the top level description from README.md.
Additionally this adds a second clarification that Klipper is a "3D
printer firmware" (as referenced in the Klipper `README.md`) in this
projects `README.md`.
Signed-off-by: Brian 'Redbeard' Harrington <redbeard@dead-city.org>