'pfsync' kernel compile requires 'pf' - documentation update for 'handbook/firewalls-pf.html' ?

[falz]

Hello,

I'm unsure what the proper ettiquite is to request a handbook change,
but -doc seemed to be the most logical match for a request. In the
handbook for 'handbook/firewalls-pf.html', it mentions that to use
pfsync, one must have it statically compiled into the kernel. However,
this also requires pf to be compiled into the kernel, or the compile
will fail. I don't have exact wording, but I'd like to suggest
somewhere (handbook, pfsync(4), sys/conf/NOTES) that this be
metnioned. It certainly seems like common sense as to why pf would
have to be compiled in to use pfsync, it may not be obvious to a user
at first.

Thanks,
--falz