Added backwards incompatibility note for refs #22845; refs #23082.

  method that is registered with the check framework. If you have an existing

  method called ``check()`` on one of these objects, you will need to rename it.

* As noted above in the "Cache" section of "Minor Features", defining the

  :setting:`TIMEOUT <CACHES-TIMEOUT>` argument of the

  :setting:`CACHES` setting as ``None`` will set the cache keys as

  "non-expiring". Previously, with the memcache backend, a

  :setting:`TIMEOUT <CACHES-TIMEOUT>` of ``0`` would set non-expiring keys,

  but this was inconsistent with the set-and-expire (i.e. no caching) behavior

  of ``set("key", "value", timeout=0)``. If you want non-expiring keys,

  please update your settings to use ``None`` instead of ``0`` as the latter

  now designates set-and-expire in the settings as well.

.. _deprecated-features-1.7:

Features deprecated in 1.7