reproduce:
        # https://github.com/intel/linux-intel-lts/commit/a2d17e22111160662f622d94e4ed6c6740330039
        git remote add intel-lts https://github.com/intel/linux-intel-lts.git
        git fetch --no-tags intel-lts 5.15/android_u
        git checkout a2d17e22111160662f622d94e4ed6c6740330039
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs