Clarify the use of Job.set_rqmt and Job.update_rqmt

sisyphus/job.py

@@ -1114,6 +1114,8 @@ def output_var(self, filename, pickle=False, backup=None):
     def set_rqmt(self, task_name, rqmt):
         """Overwrites the given requirements for this job
 
+        If this function is called more than once, only the effects of the last call are applied.
+
         :param str task_name: Which task will be affected
         :param rqmt: the new requirements
         :return:
@@ -1125,6 +1127,8 @@ def set_rqmt(self, task_name, rqmt):
     def update_rqmt(self, task_name, rqmt):
         """Updates the given requirements for this job, values not set in rqmt will not be affected.
 
+        If this function is called more than once, only the effects of the last call are applied.
+
         :param str task_name: Which task will be affected
         :param rqmt: the new requirements
         :return: