fix markup nit

Doc/whatsnew/whatsnew25.tex

@@ -1175,7 +1175,7 @@ an import would have picked up a directory as a package but no
 \file{__init__.py} was found.  (Implemented by Thomas Wouters.)
 
 To suppress these warnings, you can either supply 
-\command{-W'ignore:Not importing directory'} when running the Python
+\code{\programopt{-W}'ignore:Not importing directory'} when running the Python
 interpreter, or use the \module{warnings} module to suppress the
 message: