Consistent getopt markup

Author: ncoghlan

Doc/howto/argparse.rst

@@ -18,7 +18,7 @@ recommended command-line parsing module in the Python standard library.
    module (which may require more code to configure for a given application,
    but also allows an application to request behaviors that ``argparse``
    doesn't support), and the very low level :mod:`getopt` (which specifically
-   serves as an equivalent to ``getopt()`` from the C language).
+   serves as an equivalent to :c:func:`!getopt` from the C language).
    While neither of those modules is covered directly in this guide, many of
    the core concepts in ``argparse`` first originated in ``optparse``, so
    some aspects of this tutorial will also be relevant to ``optparse`` users.

Doc/whatsnew/3.13.rst

@@ -1660,7 +1660,7 @@ optparse
   for implementing command line applications which adhere more
   strictly than ``argparse`` does to various Unix command line
   processing conventions that originate in the behaviour of the
-  C :c:func:`getopt` function .
+  C :c:func:`!getopt` function .
   (Contributed by Alyssa Coghlan and Serhiy Storchaka in :gh:`126180`.)