Add additional docs for uncooperative ctor deprecation (#9498)

* Add additional docs for uncooperative ctor deprecation

Fixes #9488

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Break up long line

* Recommend kwonly args

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

doc/en/example/nonpython/conftest.py

@@ -18,8 +18,8 @@ class YamlFile(pytest.File):
 
 
 class YamlItem(pytest.Item):
-    def __init__(self, name, parent, spec):
-        super().__init__(name, parent)
+    def __init__(self, *, spec, **kwargs):
+        super().__init__(**kwargs)
         self.spec = spec
 
     def runtest(self):