Also add note where it should *not* be used.
https://github.com/systemd/systemd/pull/8408#discussion_r175606771
other units. Units near the top are started before units nearer to
the bottom of the chart.</para>
+ <!-- note: do not use unicode ellipsis here, because docbook will replace that
+ with three dots anyway, messing up alignment -->
<programlisting>local-fs-pre.target
|
v
systemd-journald.service loaded active running Journal Service
systemd-logind.service loaded active running Login Service
● user@1000.service loaded active running User Manager for UID 1000
-...
+…
systemd-tmpfiles-clean.timer loaded active waiting Daily Cleanup of Temporary Directories
LOAD = Reflects whether the unit definition was properly loaded.