docs/tools/update_html.py displays the follow warning for each language, and the web broswer's tab shows "index" as page title.
[WARNING] This document format requires a nonempty <title> element.
Defaulting to 'index' as the title.
To specify a title, use 'title' in metadata or --metadata title="...".
docs/tools/update_html.py
displays the follow warning for each language, and the web broswer's tab shows "index" as page title.