The custom help() is replaced by a COMMAND() description, and
--introspect-cli is added. --help now goes through the pager, like other
commands with --no-pager.
Synopses are adjusted. --user-unit/--unit without any unit names is
technically allowed, but not very meaningful, since it's the same as
the default mode. So [] is dropped. And the prog help string is then
adjusted to match the man page.
Zbigniew Jędrzejewski-Szmek
d768cdcceb