Fix link to ExtendedStatus.  [skip ci]
href="https://www.freedesktop.org/software/systemd/man/systemd.service.html">systemd.service(5)</a>
for more information). The module is activated if loaded.</p>
- <p><directive module="mod_status">ExtendedStatus</directive> is
+ <p><directive module="core">ExtendedStatus</directive> is
enabled by default if the module is loaded. If <directive
- module="mod_status">ExtendedStatus</directive> is not disabled in
+ module="core">ExtendedStatus</directive> is not disabled in
the configuration, run-time load and request statistics are made
available in the <code>systemctl status</code> output.</p>
</summary>
