Mega mdoc(7) update:

Mega mdoc(7) update:

	* Introduce a .Dx macro, for meaning `DragonFly'.

	* Use the .Dx macro where we mean `DragonFly' and
	  revert to using .Fx where we mean `FreeBSD'.

	* Update various sentences, paragraphs to be in
	  context with DragonFly, and mention FreeBSD as
	  required in HISTORY sections.

	* Fix mdoc(7) markup wherever possible.

	* Use .Fx wherever possible, and minimize the use
	  of FreeBSD in favour of .Fx.  Do the same for
	  `OpenBSD' and `NetBSD' by using `.Ox' and `.Nx'
	  respectively.

	* Correct a confusion of `FreeBSD' is `DragonFly'
	  left by a previous commit to some of the manual
	  pages, by using the appropriate .Dx/.Fx entities.

NOTE: contrib/ and other manual pages such as sysintall(8)
manual pages are left untouched, because the former should
not be modified directly and the latter has reached
'End of Life' stage.

Submitted by:
Aaron Malone <aaron@munge.net>, Hiten Pandya <hmp@backplane.com>