[3.12] Normalize cdecl formatting as found elsewhere on ctypes.rst (GH-121379) (#124057)

Co-authored-by: utkonos <utkonos@users.noreply.github.com>

Author: miss-islington

Doc/library/ctypes.rst

@@ -51,7 +51,7 @@ function call fails.
 
 
 Here are some examples for Windows. Note that ``msvcrt`` is the MS standard C
-library containing most standard C functions, and uses the cdecl calling
+library containing most standard C functions, and uses the ``cdecl`` calling
 convention::
 
    >>> from ctypes import *