[3.12] gh-72971: Clarify the special no-TypeError behavior for equality (GH-110729) (#116254)

(cherry picked from commit 67f742e)

Co-authored-by: Gouvernathor <[email protected]>

Author: miss-islington

Doc/reference/datamodel.rst

@@ -1805,12 +1805,15 @@ Basic customization
    rather, :meth:`__lt__` and :meth:`__gt__` are each other's reflection,
    :meth:`__le__` and :meth:`__ge__` are each other's reflection, and
    :meth:`__eq__` and :meth:`__ne__` are their own reflection.
-   If the operands are of different types, and right operand's type is
+   If the operands are of different types, and the right operand's type is
    a direct or indirect subclass of the left operand's type,
    the reflected method of the right operand has priority, otherwise
    the left operand's method has priority.  Virtual subclassing is
    not considered.
 
+   When no appropriate method returns any value other than :data:`NotImplemented`, the
+   ``==`` and ``!=`` operators will fall back to ``is`` and ``is not``, respectively.
+
 .. method:: object.__hash__(self)
 
    .. index::