I know it isn't a good thing to have many copy-and-pasted contents
(set file descriptions etc) in all MD files, but it's much more annoying
to maintain a bunch of .if \n [${MACHINE}] conditionals for all ports
and maintainers rarely notice that they also have to prepare or update
MD contents in MI content file with messy ifdefs.
XXX: of course common text should be shared by mdoc macro etc.
but I doubt playing mdoc(7) is really worth...
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