Expand explanation of ReturnToService in slurm.conf

doc/man/man5/slurm.conf.5

@@ -1796,10 +1796,14 @@ valid configuration only if it was set DOWN due to being non\-responsive.
 If the node was set DOWN for any other reason (low memory, prolog failure,
 epilog failure, unexpected reboot, etc.), its state will not automatically
 be changed.
+A node registers with a valid configuration if its memory, GRES, CPU count,
+etc. are equal to or greater than the values configured in slurm.conf.
 .TP
 \fB2\fR
 A DOWN node will become available for use upon registration with a
 valid configuration.  The node could have been set DOWN for any reason.
+A node registers with a valid configuration if its memory, GRES, CPU count,
+etc. are equal to or greater than the values configured in slurm.conf.
 (Disabled on Cray ALPS systems.)
 .RE