doc: Update FreeBSD documentation tools information

based on patch from Dag-Erling Smørgrav <des@des.no>
doc: Update Red Hat documentation tools information

The old text was written in ancient times when RPM packages could be
shared more or less freely across a plethora of RPM-based Linux
distributions.  This isn't really the case anymore, so just make this
information more concrete for the Red Hat family.