Reference override_pause_level in RULES modify section

The RULES section says

    The following attributes can be overridden:

which I interpret as meaning that _only_ the attributes listed in this
section can be modified by a rule, but override_pause_level can also
be set.

Author: lverns

docs/dunst.5.pod

@@ -1021,6 +1021,10 @@ B<IMPORTANT NOTE>: This currently DOES NOT re-apply the attributes from the
 urgency_* sections. The changed urgency will only be visible in rules defined
 later. Use C<msg_urgency> to match it.
 
+=item C<override_pause_level>
+
+See B<override_pause_level>.
+
 =item C<skip_display>
 
 Setting this to true will prevent the notification from being displayed