Add return field to a docstring

code/Attack/MembersMgmtCommAttack.py

@@ -668,6 +668,7 @@ class MembersMgmtCommAttack(BaseAttack.BaseAttack):
     def _get_capture_duration(self):
         """
         Returns the duration of the input PCAP (since statistics duration seems to be incorrect)
+        :return: the duration as a string in the format seconds.microseconds
         """
         ts_date_format = "%Y-%m-%d %H:%M:%S.%f"
         ts_first_date = datetime.strptime(self.statistics.get_pcap_timestamp_start(), ts_date_format)