RFC: add text about freedesktop.org and related topics to FAQ

[Mark Linimon]

I doubt I have to explain to anyone on x11@ why we need this, but for
the doc folks, we are continually getting questions on multiple mailing
lists about the state of X on FreeBSD.

I would like to commit the following after a brief review, since it _is_
getting asked so frequently :-(  I have tried to remove as much of the
'political' side of the equation as possible in an effort to be as non-
controversial as possible.

mcl