minor: style change

draft/reference/current-op.txt

@@ -8,7 +8,7 @@ Current Operation Reporting
 
 The :method:`db.currentOp()` helper in the :program:`mongo` shell
 reports on the current operations running on the :program:`mongod`
-instance. The command returns the ``inprog`` array, which contains a
+instance. The command returns the ``inprog`` array that contains a
 document for each in progress operation. Consider the following
 example output: