fop not installed as a dependency of the docproj package

[Pau Amma]

While trying to duplicate the PDF output error reported in 
https://reviews.freebsd.org/D22708#502794 (using "make FORMATS=pdf" in 
~/doc/en_US.ISO8859-1/books/handbook), I got the following error 
instead:
...
/usr/bin/env FOP_OPTS="-Xss1024k -Xmx1431552k" /usr/local/bin/fop -c 
/usr/home/pauamma/doc/share/misc/fop.xconf book.fo -pdf book.pdf
env: /usr/local/bin/fop: No such file or directory
*** Error code 127

Stop.
make: stopped in /usr/home/pauamma/doc/en_US.ISO8859-1/books/handbook

This is apparently because that package was built with "FOP            : 
off", per "pkg info docproj". If that's deliberate, perhaps a note 
should be added to 
https://www.freebsd.org/doc/en_US.ISO8859-1/books/fdp-primer/overview.html, 
which currently says to:

# pkg install docproj subversion

and doesn't mention installing fop as well to generate .pdf files.

Opinions? Should the FOP build option be turned on by default in 
docproj, or a note added instead to install fop as well if PDF output is 
desired? (Or am I missing something obvious?)