doc: Fix html_use_opensearch of sphinx-doc.org

doc/conf.py

@@ -26,7 +26,7 @@ modindex_common_prefix = ['sphinx.']
 html_static_path = ['_static']
 html_sidebars = {'index': ['indexsidebar.html', 'searchbox.html']}
 html_additional_pages = {'index': 'index.html'}
-html_use_opensearch = 'http://sphinx-doc.org'
+html_use_opensearch = 'https://www.sphinx-doc.org/en/master'
 html_baseurl = 'https://www.sphinx-doc.org/en/master/'
 
 htmlhelp_basename = 'Sphinxdoc'