[docs] fix link searx/languages.py to new file searx/sxng_locales.py

The language settings page in the documentation reference languages.py which was
removed in commit c9cd376

Closes: https://github.com/searxng/searxng/issues/4690
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

docs/admin/settings/settings_search.rst

@@ -57,11 +57,11 @@
 
 ``default_lang``:
   Default search language - leave blank to detect from browser information or
-  use codes from :origin:`searx/languages.py`.
+  use codes from :origin:`searx/sxng_locales.py`.
 
 ``languages``:
   List of available languages - leave unset to use all codes from
-  :origin:`searx/languages.py`.  Otherwise list codes of available languages.
+  :origin:`searx/sxng_locales.py`.  Otherwise list codes of available languages.
   The ``all`` value is shown as the ``Default language`` in the user interface
   (in most cases, it is meant to send the query without a language parameter ;
   in some cases, it means the English language) Example: