reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git/commit/?id=ca6d0d838cc43107728a2f2f373fed003e6d935f
        git remote add snitzer https://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git
        git fetch --no-tags snitzer snitm-kernel-6.12/delstid-localio
        git checkout ca6d0d838cc43107728a2f2f373fed003e6d935f
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs