Doc: fix default role usage (except in unittest mock docs)

Doc/howto/pyporting.rst

@@ -535,7 +535,7 @@ Update ``map`` for imbalanced input sequences
 '''''''''''''''''''''''''''''''''''''''''''''
 
 With Python 2, when ``map`` was given more than one input sequence it would pad
-the shorter sequences with `None` values, returning a sequence as long as the
+the shorter sequences with ``None`` values, returning a sequence as long as the
 longest input sequence.
 
 With Python 3, if the input sequences to ``map`` are of unequal length, ``map``

Doc/library/ctypes.rst

@@ -1090,7 +1090,7 @@ As we can easily check, our array is sorted now::
    outside of Python's control (e.g. by the foreign code that calls the
    callback), ctypes creates a new dummy Python thread on every invocation. This
    behavior is correct for most purposes, but it means that values stored with
-   `threading.local` will *not* survive across different callbacks, even when
+   :class:`threading.local` will *not* survive across different callbacks, even when
    those calls are made from the same C thread.
 
 .. _ctypes-accessing-values-exported-from-dlls: