[5.0.x] Fixed #35141 -- Clarified the expected type of CACHE_MIDDLEWARE_SECONDS setting.

Backport of a5365339eaee043895a79dbbdd7462f1399136e5 from main

docs/ref/settings.txt

@@ -273,8 +273,8 @@ See :doc:`/topics/cache`.
 
 Default: ``600``
 
-The default number of seconds to cache a page for the :ref:`cache middleware
-<the-per-site-cache>`.
+The default integer number of seconds to cache a page for the
+:ref:`cache middleware <the-per-site-cache>`.
 
 See :doc:`/topics/cache`.
 

docs/topics/cache.txt

@@ -608,8 +608,9 @@ entire site. You'll need to add
 Then, add the following required settings to your Django settings file:
 
 * :setting:`CACHE_MIDDLEWARE_ALIAS` -- The cache alias to use for storage.
-* :setting:`CACHE_MIDDLEWARE_SECONDS` -- The number of seconds each page should
-  be cached.
+* :setting:`CACHE_MIDDLEWARE_SECONDS` -- The integer number of seconds each
+  page should be cached.
+
 * :setting:`CACHE_MIDDLEWARE_KEY_PREFIX` -- If the cache is shared across
   multiple sites using the same Django installation, set this to the name of
   the site, or some other string that is unique to this Django instance, to