bpo-31667: Fix gettext related links. (#3860)

* Fix incorrect links.
* Remove redundant links.
* Add signatures and index entries for gettext related
functions in the locale module.

Doc/library/gettext.rst

@@ -134,7 +134,7 @@ Class-based API
 
 The class-based API of the :mod:`gettext` module gives you more flexibility and
 greater convenience than the GNU :program:`gettext` API.  It is the recommended
-way of localizing your Python applications and modules.  :mod:`gettext` defines
+way of localizing your Python applications and modules.  :mod:`!gettext` defines
 a "translations" class which implements the parsing of GNU :file:`.mo` format
 files, and has methods for returning strings. Instances of this "translations"
 class can also install themselves in the built-in namespace as the function
@@ -219,7 +219,7 @@ Translation classes are what actually implement the translation of original
 source file message strings to translated message strings. The base class used
 by all translation classes is :class:`NullTranslations`; this provides the basic
 interface you can use to write your own specialized translation classes.  Here
-are the methods of :class:`NullTranslations`:
+are the methods of :class:`!NullTranslations`:
 
 
 .. class:: NullTranslations(fp=None)
@@ -247,13 +247,13 @@ are the methods of :class:`NullTranslations`:
 
    .. method:: gettext(message)
 
-      If a fallback has been set, forward :meth:`.gettext` to the fallback.
+      If a fallback has been set, forward :meth:`!gettext` to the fallback.
       Otherwise, return *message*.  Overridden in derived classes.
 
 
    .. method:: ngettext(singular, plural, n)
 
-      If a fallback has been set, forward :meth:`ngettext` to the fallback.
+      If a fallback has been set, forward :meth:`!ngettext` to the fallback.
       Otherwise, return *singular* if *n* is 1; return *plural* otherwise.
       Overridden in derived classes.
 
@@ -261,7 +261,7 @@ are the methods of :class:`NullTranslations`:
    .. method:: lgettext(message)
    .. method:: lngettext(singular, plural, n)
 
-      Equivalent to :meth:`.gettext` and :meth:`ngettext`, but the translation
+      Equivalent to :meth:`.gettext` and :meth:`.ngettext`, but the translation
       is returned as a byte string encoded in the preferred system encoding
       if no encoding was explicitly set with :meth:`set_output_charset`.
       Overridden in derived classes.

Doc/library/locale.rst

@@ -551,17 +551,23 @@ library.
 Access to message catalogs
 --------------------------
 
+.. function:: gettext(msg)
+.. function:: dgettext(domain, msg)
+.. function:: dcgettext(domain, msg, category)
+.. function:: textdomain(domain)
+.. function:: bindtextdomain(domain, dir)
+
 The locale module exposes the C library's gettext interface on systems that
-provide this interface.  It consists of the functions :func:`gettext`,
-:func:`dgettext`, :func:`dcgettext`, :func:`textdomain`, :func:`bindtextdomain`,
-and :func:`bind_textdomain_codeset`.  These are similar to the same functions in
+provide this interface.  It consists of the functions :func:`!gettext`,
+:func:`!dgettext`, :func:`!dcgettext`, :func:`!textdomain`, :func:`!bindtextdomain`,
+and :func:`!bind_textdomain_codeset`.  These are similar to the same functions in
 the :mod:`gettext` module, but use the C library's binary format for message
 catalogs, and the C library's search algorithms for locating message catalogs.
 
 Python applications should normally find no need to invoke these functions, and
 should use :mod:`gettext` instead.  A known exception to this rule are
 applications that link with additional C libraries which internally invoke
-:c:func:`gettext` or :func:`dcgettext`.  For these applications, it may be
+:c:func:`gettext` or :c:func:`dcgettext`.  For these applications, it may be
 necessary to bind the text domain, so that the libraries can properly locate
 their message catalogs.