Document CPU count increase for mem_per_cpu limit

Document that if a job's memory per CPU limit exceeds the system
limit, that the job's memory limit is decreased and it's CPU count
increased automatically.

doc/man/man5/slurm.conf.5

@@ -690,6 +690,7 @@ are allocated to jobs (\fBSelectType=select/cons_res\fR).
 The default value is 0 (unlimited).
 Also see \fBDefMemPerNode\fR and \fBMaxMemPerCPU\fR.
 \fBDefMemPerCPU\fR and \fBDefMemPerNode\fR are mutually exclusive.
+
 NOTE: Enforcement of memory limits currently requires enabling of
 accounting, which samples memory use on a periodic basis (data need
 not be stored, just collected).
@@ -704,6 +705,7 @@ resources are shared (\fBShared=yes\fR or \fBShared=force\fR).
 The default value is 0 (unlimited).
 Also see \fBDefMemPerCPU\fR and \fBMaxMemPerNode\fR.
 \fBDefMemPerCPU\fR and \fBDefMemPerNode\fR are mutually exclusive.
+
 NOTE: Enforcement of memory limits currently requires enabling of
 accounting, which samples memory use on a periodic basis (data need
 not be stored, just collected).
@@ -1350,10 +1352,15 @@ are allocated to jobs (\fBSelectType=select/cons_res\fR).
 The default value is 0 (unlimited).
 Also see \fBDefMemPerCPU\fR and \fBMaxMemPerNode\fR.
 \fBMaxMemPerCPU\fR and \fBMaxMemPerNode\fR are mutually exclusive.
+
 NOTE: Enforcement of memory limits currently requires enabling of
 accounting, which samples memory use on a periodic basis (data need
 not be stored, just collected).
 
+NOTE: If a job specifies a memory per CPU limit that exceeds this system limit,
+that job's count of CPUs per task will automatically be increased. This may
+result in the job failing due to CPU count limits.
+
 .TP
 \fBMaxMemPerNode\fR
 Maximum real memory size available per allocated node in MegaBytes.
@@ -1364,6 +1371,7 @@ resources are shared (\fBShared=yes\fR or \fBShared=force\fR).
 The default value is 0 (unlimited).
 Also see \fBDefMemPerNode\fR and \fBMaxMemPerCPU\fR.
 \fBMaxMemPerCPU\fR and \fBMaxMemPerNode\fR are mutually exclusive.
+
 NOTE: Enforcement of memory limits currently requires enabling of
 accounting, which samples memory use on a periodic basis (data need
 not be stored, just collected).