Use impl-detail:: markup instead of note::

Author: furkanonder

Doc/c-api/object.rst

@@ -286,7 +286,8 @@ Object Protocol
    >>> D.__base__
    <class 'B'>
 
-   Note that behavior of the ``__base__`` attribute is dependent on the :term:`CPython` implementation.
+   .. impl-detail::
+      Note that behavior of the ``__base__`` attribute is dependent on the :term:`CPython` implementation.
 
 .. c:function:: int PyObject_IsInstance(PyObject *inst, PyObject *cls)
 

Doc/library/stdtypes.rst

@@ -5453,7 +5453,7 @@ types, where they are relevant.  Some of these are not reported by the
   involving base classes that contribute to the instance layout.
   ``__base__`` is the base class that is involved in that chain.
 
-  .. note::
+  .. impl-detail::
     The behavior of the ``__base__`` attribute is dependent on the :term:`CPython` implementation.
 
 .. attribute:: definition.__name__

Doc/reference/datamodel.rst

@@ -860,7 +860,7 @@ Custom classes
           involving base classes that contribute to the instance layout.
           ``__base__`` is the base class that is involved in that chain.
 
-          .. note::
+          .. impl-detail::
             The behavior of the ``__base__`` attribute is dependent on the :term:`CPython` implementation.
 
       :attr:`__doc__`