gh-61481: Document that memoryview, range, and slice cannot be subclassed

Among the built-in classes that can't be subclassed, only bool documents
it. memoryview, range, and slice behave the same but say nothing, so it
can only be found out by trying. Add the same note to those three.

The wording mirrors the existing bool entry, minus the "further" that
applies only to bool (which subclasses int).

Author: soreavis

Doc/library/functions.rst

@@ -1292,6 +1292,8 @@ are always available.  They are listed here in alphabetical order.
    Return a "memory view" object created from the given argument.  See
    :ref:`typememoryview` for more information.
 
+   This class cannot be subclassed.
+
 
 .. function:: min(iterable, /, *, key=None)
               min(iterable, /, *, default, key=None)
@@ -1749,6 +1751,8 @@ are always available.  They are listed here in alphabetical order.
    Rather than being a function, :class:`range` is actually an immutable
    sequence type, as documented in :ref:`typesseq-range` and :ref:`typesseq`.
 
+   This class cannot be subclassed.
+
 
 .. function:: repr(object, /)
 
@@ -1920,6 +1924,8 @@ are always available.  They are listed here in alphabetical order.
    See :func:`itertools.islice` for an alternate version that returns an
    :term:`iterator`.
 
+   This class cannot be subclassed.
+
    .. attribute:: slice.start
                   slice.stop
                   slice.step