sysutils/vzvol was updated to version 0.7.0 upstream.
This update now includes a manpage, and upstream has remedied the incorrect location of vzvol. Previously it would be stored in PREFIX/bin, but as a system utility, it belonged in PREFIX/sbin.
That's my bad (upstream/maintainer)
I opened a diff at https://reviews.freebsd.org/D15707 to apply this update to ports/HEAD
(If I've screwed up the manpage install, or need to add anything to make sure the old PREFIX/bin/vzvol gets removed in favor of PREFIX/sbin/vzvol, let me know! I'm still kind of new at this whole maintainer thing.)
A commit references this bug:
Date: Wed Jun 13 16:12:36 UTC 2018
New revision: 472332
sysutils/vzvol: update 0.6.4 -> 0.7.0
Submitted by: firstname.lastname@example.org (maintainer)
Reviewed by: krion, pi
Differential Revision: https://reviews.freebsd.org/D15707