fix docstring

--HG--
branch : trunk

py/_plugin/pytest_monkeypatch.py

@@ -68,10 +68,9 @@ def pytest_funcarg__monkeypatch(request):
         monkeypatch.syspath_prepend(path)
 
     All modifications will be undone when the requesting 
-    test function finished its execution.  For the ``del`` 
-    methods the ``raising`` parameter determines if a
-    KeyError or AttributeError will be raised if the
-    deletion has no target. 
+    test function finished its execution.  The ``raising`` 
+    parameter determines if a KeyError or AttributeError 
+    will be raised if the set/deletion operation has no target. 
     """
     monkeypatch = MonkeyPatch()
     request.addfinalizer(monkeypatch.undo)