Sphinx provides three default substitutions |release|, |version| and |today|
see: https://www.sphinx-doc.org/en/master/usage/restructuredtext/roles.html#default-substitutions
but their usage fails with (ERROR/3) Undefined substitution referenced:"release"
see: https://integration.wikimedia.org/ci/job/pywikibot-core-tox-doc-docker/14497/console
See also: https://stackoverflow.com/questions/41269319/why-the-substitution-version-is-not-working-on-sphinx
As found out in https://github.com/sphinx-doc/sphinx/issues/9045 this is a rstcheck issue