reproduce:
        git checkout d3f825032091fc14c7d5e34bcd54317ae4246903
        b4 shazam https://lore.kernel.org/r/20250618111544.22602-4-bagasdotme@gmail.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 3.4.3
        make htmldocs