Reworded parts of the constants documentation

Addresses #22336 (comment), #22336 (comment) & #22336 (comment)

Author: Bas van Beek

Doc/library/constants.rst

@@ -19,20 +19,21 @@ A small number of constants live in the built-in namespace.  They are:
 
 .. data:: None
 
-   The sole value of the type :data:`types.NoneType`. ``None`` is frequently used to
-   represent the absence of a value, as when default arguments are not passed to a
-   function. Assignments to ``None`` are illegal and raise a :exc:`SyntaxError`.
+   An object frequently used to represent the absence of a value, as when
+   default arguments are not passed to a function. Assignments to ``None``
+   are illegal and raise a :exc:`SyntaxError`.
+   ``None`` is the sole instance of the :data:`NoneType` type.
 
 
 .. data:: NotImplemented
 
-   Sole value of the type :data:`types.NotImplementedType` and a
-   special value which should be returned by the binary special methods
+   A special value which should be returned by the binary special methods
    (e.g. :meth:`__eq__`, :meth:`__lt__`, :meth:`__add__`, :meth:`__rsub__`,
    etc.) to indicate that the operation is not implemented with respect to
    the other type; may be returned by the in-place binary special methods
    (e.g. :meth:`__imul__`, :meth:`__iand__`, etc.) for the same purpose.
    It should not be evaluated in a boolean context.
+   ``NotImplemented`` is the sole instance of the :data:`types.NotImplementedType` type.
 
    .. note::
 
@@ -60,9 +61,9 @@ A small number of constants live in the built-in namespace.  They are:
 .. index:: single: ...; ellipsis literal
 .. data:: Ellipsis
 
-   The same as the ellipsis literal "``...``" and sole value of the type
-   :data:`types.EllipsisType`. Special value used mostly in conjunction
+   The same as the ellipsis literal "``...``". Special value used mostly in conjunction
    with extended slicing syntax for user-defined container data types.
+   ``Ellipsis`` is the sole instance of the :data:`types.EllipsisType` type.
 
 
 .. data:: __debug__