Building documentation does not seem to work as expected

[musicinmybrain]

$ gh repo clone mmlabs-mindmaze/mmlib
$ cd mmlib
$ python3.11 -m venv _e
(_e) $ pip install sphinx sphinx-rtd-theme linuxdoc
(_e) $ meson setup _build
(_e) $ ninja -C _build

Both when trying to generate man pages and when trying to generate HTML documentation, there are many errors of the form

/home/ben/src/mmlib/doc/alloc.rst:4: ERROR: Error in "kernel-doc" directive:
unknown option: "headers".

.. kernel-doc:: src/alloc.c
    :module: alloc
    :headers: mmlib.h
    :functions: mm_aligned_alloc, mm_aligned_free

The documentation build “succeeds” but the individual pages that would have been generated via linuxdoc, e.g. _build/doc/html/alloc.html, have no content, the man page build reports WARNING: no "man_pages" config value nor manual section found; no manual pages will be written, and _build/doc/man3/ is empty.

Am I missing something, or is this no longer working as expected with current versions of sphinx and/or linuxdoc?