update format of --checkpoint option input

doc/html/checkpoint_blcr.shtml

@@ -44,9 +44,8 @@ Basic familiarity with SLURM commands is assumed.</p>
 checkpoints of the job step.
 By default, the job step will have no checkpoints created.
 Acceptable time formats include "minutes", "minutes:seconds",
-"hours:minutes:seconds", "days\-hours", "days\-hours:minutes" and
-"days\-hours:minutes:seconds".
-</li>
+"hours:minutes:seconds", "days-hours", "days-hours:minutes" and
+"days-hours:minutes:seconds".</li>
 <li><b>--checkpoint-dir</b>:Specify the directory where the checkpoint image
 files of a job step will be stored.
 The default value is the current working directory.
@@ -116,8 +115,12 @@ execution of the tasks from the previous checkpoint.</p>
 
 <p>Several options have been added to support checkpoint restart:</p>
 <ul>
-<li><b>--checkpoint</b>: Specify the interval between periodic checkpoint
-of a batch job, in seconds</li>
+<li><b>--checkpoint</b>: Specifies the interval between periodic checkpoint
+of a batch job.
+By default, the job will have no checkpoints created.
+Acceptable time formats include "minutes", "minutes:seconds",
+"hours:minutes:seconds", "days-hours", "days-hours:minutes" and
+"days-hours:minutes:seconds".</li>
 <li><b>--checkpoint-dir</b>:Specify the directory when the checkpoint image
 files of a batch job will be stored.
 The default value is the current working directory.