Issue #19795: Mark up None as literal text.

Doc/howto/descriptor.rst

@@ -302,7 +302,7 @@ The output suggests that bound and unbound methods are two different types.
 While they could have been implemented that way, the actual C implementation of
 :c:type:`PyMethod_Type` in :source:`Objects/classobject.c` is a single object
 with two different representations depending on whether the :attr:`im_self`
-field is set or is *NULL* (the C equivalent of *None*).
+field is set or is *NULL* (the C equivalent of ``None``).
 
 Likewise, the effects of calling a method object depend on the :attr:`im_self`
 field. If set (meaning bound), the original function (stored in the

Doc/howto/logging.rst

@@ -764,7 +764,7 @@ In Python 3.2 and later, the behaviour is as follows:
   The handler's level is set to ``WARNING``, so all events at this and
   greater severities will be output.
 
-To obtain the pre-3.2 behaviour, ``logging.lastResort`` can be set to *None*.
+To obtain the pre-3.2 behaviour, ``logging.lastResort`` can be set to ``None``.
 
 .. _library-config:
 

Doc/howto/sorting.rst

@@ -24,7 +24,7 @@ returns a new sorted list::
     [1, 2, 3, 4, 5]
 
 You can also use the :meth:`list.sort` method. It modifies the list
-in-place (and returns *None* to avoid confusion). Usually it's less convenient
+in-place (and returns ``None`` to avoid confusion). Usually it's less convenient
 than :func:`sorted` - but if you don't need the original list, it's slightly
 more efficient.