Clarified warning about date-based generic views.

docs/ref/class-based-views.txt

@@ -750,9 +750,15 @@ DateMixin
 
         When :doc:`time zone support </topics/i18n/timezones>` is enabled and
         ``date_field`` is a ``DateTimeField``, dates are assumed to be in the
-        current time zone. As a consequence, if you have implemented per-user
-        time zone selection, users living in different time zones may view a
-        different set of objects at the same URL.
+        current time zone. Otherwise, the queryset could include objects from
+        the previous or the next day in the end user's time zone.
+
+        .. warning::
+
+            In this situation, if you have implemented per-user time zone
+            selection, the same URL may show a different set of objects,
+            depending on the end user's time zone. To avoid this, you should
+            use a ``DateField`` as the ``date_field`` attribute.
 
     .. attribute:: allow_future