Update limitations for 5.1.0b3 release

Author: timgraham

source/limitations-upcoming.txt

@@ -38,6 +38,7 @@ types of unsupported {+framework+} and MongoDB features:
 - :ref:`django-limitations-query`
 - :ref:`django-limitations-management`
 - :ref:`django-limitations-migration`
+- :ref:`django-limitations-caching`
 - :ref:`django-limitations-performance`
 
 .. _django-limitations-transactions:
@@ -131,8 +132,6 @@ Querying Limitations
 
 {+django-odm+} does not support the following ``QuerySet`` API methods:
 
-- ``dates()``
-- ``datetimes()``
 - ``prefetch_related()``
 - ``extra()``
 
@@ -171,8 +170,10 @@ Database Functions
 - ``SHA1``, ``SHA224``, ``SHA256``, ``SHA384``, ``SHA512``
 - ``Sign``
 
-The ``tzinfo`` parameter of the ``Trunc`` database functions doesn't work
-properly because MongoDB converts the result back to UTC.
+- The ``tzinfo`` parameter of the
+  :class:`~django.db.models.functions.TruncDate` and
+  :class:`~django.db.models.functions.TruncTime` database functions isn't
+  supported.
 
 .. _django-limitations-management:
 
@@ -181,7 +182,7 @@ Unsupported Management Commands
 
 The following ``django-admin`` commands are unsupported:
 
-- ``createcachetable``
+- ``createcachetable`` (see :ref:`django-limitations-caching`)
 - ``inspectdb``
 
 .. _django-limitations-migration:
@@ -198,6 +199,18 @@ Migration Limitations
 - `DDL Transactions <{+django-docs+}/topics/migrations/#transactions>`__.
 - The ``migrate --fake-initial`` option.
 
+.. _django-limitations-caching:
+
+Caching
+~~~~~~~
+
+Database caching uses this {+django-odm+}'s ``createcachecollection`` command
+rather Django's SQL-specific ``createcachetable``.
+
+Secondly, you must use the ``django_mongodb_backend.cache.MongoDBCache``
+backend rather than Django's built-in database cache backend,
+``django.core.cache.backends.db.DatabaseCache``.
+
 .. _django-limitations-performance:
 
 Performance
@@ -234,7 +247,6 @@ We plan to support the following MongoDB features in the GA release:
   by using the Django API
 - Queryable Encryption and Client-side Field Level Encryption
 - Database transactions
-- Storage of cached data in the database
 
 We plan to support the following MongoDB features in future post-GA releases: