reproduce:
        # https://github.com/LinuxSecurityModule/kernel/commit/fed0449b38a2791712e8c3cd0fe08cb50de2e86d
        git remote add linuxsecuritymodule https://github.com/LinuxSecurityModule/kernel
        git fetch --no-tags linuxsecuritymodule main
        git checkout fed0449b38a2791712e8c3cd0fe08cb50de2e86d
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs