reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?id=9e0190e84f2ecf5ff7314441655d71913095654e
        git remote add kees https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
        git fetch --no-tags kees dev/v7.0-rc2/obt
        git checkout 9e0190e84f2ecf5ff7314441655d71913095654e
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs