Update documentation for users to use flask-caching instead of the deprecated Werkzeug cache

docs/patterns/caching.rst

@@ -10,60 +10,9 @@ still be good enough if they were 5 minutes old.  So then the idea is that
 you actually put the result of that calculation into a cache for some
 time.
 
-Flask itself does not provide caching for you, but Werkzeug, one of the
-libraries it is based on, has some very basic cache support.  It supports
-multiple cache backends, normally you want to use a memcached server.
+Flask itself does not provide caching for you, but `Flask-Caching`_, an
+extentions for Flask does. Flask-Caching supports various backends, and it is
+even possible to develop your own caching backend.
 
-Setting up a Cache
-------------------
 
-You create a cache object once and keep it around, similar to how
-:class:`~flask.Flask` objects are created.  If you are using the
-development server you can create a
-:class:`~werkzeug.contrib.cache.SimpleCache` object, that one is a simple
-cache that keeps the item stored in the memory of the Python interpreter::
-
-    from werkzeug.contrib.cache import SimpleCache
-    cache = SimpleCache()
-
-If you want to use memcached, make sure to have one of the memcache modules
-supported (you get them from `PyPI <https://pypi.org/>`_) and a
-memcached server running somewhere.  This is how you connect to such an
-memcached server then::
-
-    from werkzeug.contrib.cache import MemcachedCache
-    cache = MemcachedCache(['127.0.0.1:11211'])
-
-If you are using App Engine, you can connect to the App Engine memcache
-server easily::
-
-    from werkzeug.contrib.cache import GAEMemcachedCache
-    cache = GAEMemcachedCache()
-
-Using a Cache
--------------
-
-Now how can one use such a cache?  There are two very important
-operations: :meth:`~werkzeug.contrib.cache.BaseCache.get` and
-:meth:`~werkzeug.contrib.cache.BaseCache.set`.  This is how to use them:
-
-To get an item from the cache call
-:meth:`~werkzeug.contrib.cache.BaseCache.get` with a string as key name.
-If something is in the cache, it is returned.  Otherwise that function
-will return ``None``::
-
-    rv = cache.get('my-item')
-
-To add items to the cache, use the :meth:`~werkzeug.contrib.cache.BaseCache.set`
-method instead.  The first argument is the key and the second the value
-that should be set.  Also a timeout can be provided after which the cache
-will automatically remove item.
-
-Here a full example how this looks like normally::
-
-    def get_my_item():
-        rv = cache.get('my-item')
-        if rv is None:
-            rv = calculate_value()
-            cache.set('my-item', rv, timeout=5 * 60)
-        return rv
+.. _Flask-Caching: https://flask-caching.readthedocs.io/en/latest/