address documentation oversight, kill backticks

Author: RonnyPfannschmidt

doc/en/parametrize.rst

@@ -117,7 +117,7 @@ for example with the builtin ``mark.xfail``::
 
   This was an initial hack to support the feature but soon was demonstrated to be incomplete,
   broken for passing functions or applying multiple marks with the same name but different parameters.
-  The old syntax will be removed in `pytest 4.0`.
+  The old syntax will be removed in pytest-4.0.
 
 
 Let's run this::