Added jobacct_gather plugin requirement to sstat man page

doc/man/man1/sstat.1

@@ -29,8 +29,13 @@ command displays job status data for any job running on the system.
 .PP
 For the non\-root user, the
 .BR "sstat "
-command limits the display of job status data to jobs that were
-launched with their own user identifier (UID).
+output is limited to the user's jobs.
+
+.PP
+Note:  the
+.BR "sstat "
+command requires that the \f3jobacct_gather\fP plugin be installed and
+operational.
 
 .TP
 \f3\-a \fP\f3,\fP \f3\-\-allsteps\fP