commands: use python style commends to describe methods

Change-Id: Iccc9f01769ee9274d01036d3fbbc161d8bca7628
diff --git a/pySim/commands.py b/pySim/commands.py
index 7d09fa9..805fe61 100644
--- a/pySim/commands.py
+++ b/pySim/commands.py
@@ -283,9 +283,8 @@
 			pdu = '80cb000000'
 		return self._tp.send_apdu_checksw(pdu)
 
-	# TS 102 221 Section 11.3.1
 	def retrieve_data(self, ef, tag:int):
-		"""Execute RETRIEVE DATA.
+		"""Execute RETRIEVE DATA, see also TS 102 221 Section 11.3.1.
 
 		Args
 			ef : string or list of strings indicating name or path of transparent EF