Add thai_wikipedia_titles to corpus API documentation (#1285)

* Initial plan

* Add thai_wikipedia_titles documentation to corpus.rst

Co-authored-by: wannaphong <8536487+wannaphong@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wannaphong <8536487+wannaphong@users.noreply.github.com>

Author: Copilot

docs/api/corpus.rst

@@ -72,6 +72,11 @@ thai_stopwords
 .. autofunction:: thai_stopwords
    :noindex:
 
+thai_wikipedia_titles
+~~~~~~~~~~~~~~~~~~~~~
+.. autofunction:: thai_wikipedia_titles
+   :noindex:
+
 thai_words
 ~~~~~~~~~~
 .. autofunction:: thai_words