reproduce:
        # https://github.com/gourryinverse/linux/commit/e9dd3c30fc0be8eda22f834894fcfe47c5cab4fc
        git remote add gourryinverse https://github.com/gourryinverse/linux
        git fetch --no-tags gourryinverse scratch/gourry/managed_nodes/rfc5
        git checkout e9dd3c30fc0be8eda22f834894fcfe47c5cab4fc
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs