update documentation references for node inheritance

changelog/8447.deprecation.rst

@@ -1,4 +1,4 @@
 Defining a custom pytest node type which is both an item and a collector now issues a warning.
 It was never sanely supported and triggers hard to debug errors.
 
-Instead, a separate collector node should be used, which collects the item. See :ref:`nonpython` for an example.
+Instead, a separate collector node should be used, which collects the item. See :ref:`non-python tests` for an example.

src/_pytest/nodes.py

@@ -653,7 +653,8 @@ def __init_subclass__(cls) -> None:
                 f"{cls.__name__} is an Item subclass and should not be a collector, "
                 f"however its bases {problems} are collectors.\n"
                 "Please split the Collectors and the Item into separate node types.\n"
-                "TODO: doc link",
+                "Pytest Doc example: https://docs.pytest.org/en/latest/example/nonpython.html\n"
+                "example pull request on a plugin: https://github.com/asmeurer/pytest-flakes/pull/40/",
                 PytestWarning,
             )
 

testing/test_nodes.py

@@ -46,7 +46,7 @@ def test_subclassing_both_item_and_collector_warns(request, tmp_path: Path) -> N
         PytestWarning,
         match=(
             "(?m)SoWrong is an Item subclass and should not be a collector, however its bases File are collectors.\n"
-            "Please split the Collectors and the Item into separate node types.\nTODO:.*"
+            "Please split the Collectors and the Item into separate node types.\n.*"
         ),
     ):