This assumes that the documentation is installed in /usr/share/doc,
which is true on Debian but might not be true elsewhere. Since the
upstream Makefile doesn't install userv.service anyway, I'm assuming
that it's meant to be manually installed (and fettled) on non-Debian
systems anyway.
[Unit]
Description=User services (security boundary) daemon
+Documentation=man:uservd(8)
+Documentation=file:/usr/share/doc/userv/spec.html/index.html
After=syslog.target remote-fs.target
[Service]