libcxx/docs/ReleaseNotes.rst

.. include:: ReleaseNotes/21.rst

.. Make sure to reference the non-live release notes in a toctree to avoid Sphinx errors.
.. toctree::
    :hidden:

    ReleaseNotes/20

.. The release notes are in versioned files, but we make sure to keep publishing
.. them in an unversioned ReleaseNotes.html page for external sites to reference.