Document how slurmctld -v option is preserved

doc/man/man5/slurm.conf.5

@@ -2048,6 +2048,9 @@ The default value is "root".
 \fBSlurmctldDebug\fR
 The level of detail to provide \fBslurmctld\fR daemon's logs.
 The default value is \fBinfo\fR.
+If the \fBslurmctld\fR daemon is initiated with \-v or \-\-verbose options,
+that debug level will be preserve or restored upon reconfiguration.
+
 .RS
 .TP 10
 \fBquiet\fR