fixed the mistake in using update job web page

In page "create job" configuration interval help information
is following some format,but when "update" is not the same.

Change-Id: I83761bbea9d6fd4b226254a8a018d27a792def1c

disaster_recovery/jobs/workflows/update_job.py

@@ -41,7 +41,15 @@ class InfoConfigurationAction(workflows.Action):
     schedule_interval = forms.CharField(
         label=_("Interval"),
         required=False,
-        help_text=_("Repeat this configuration in a minutes interval."))
+        help_text=_("""Set the interval in the following format:
+                       continuous,
+                       N weeks,
+                       N days,
+                       N hours,
+                       N minutes,
+                       N seconds,
+                       If no start date is provided the job
+                       will start immediately"""))
 
     schedule_end_date = forms.CharField(
         label=_("End Date and Time"),