Recommend kwonly args

doc/en/deprecations.rst

@@ -217,7 +217,7 @@ should be turned into:
 .. code-block:: python
 
     class CustomItem(pytest.Item):
-        def __init__(self, additional_arg, **kwargs):
+        def __init__(self, *, additional_arg, **kwargs):
             super().__init__(**kwargs)
             self.additional_arg = additional_arg
 

doc/en/example/nonpython/conftest.py

@@ -18,7 +18,7 @@ class YamlFile(pytest.File):
 
 
 class YamlItem(pytest.Item):
-    def __init__(self, spec, **kwargs):
+    def __init__(self, *, spec, **kwargs):
         super().__init__(**kwargs)
         self.spec = spec