message: Clarify docs on Redis package required for caching
diff: @@ -240,9 +240,11 @@ complies with the Flask-Cache specifications.
  Flask-Cache supports multiple caching backends (Redis, Memcached,
  SimpleCache (in-memory), or the local filesystem). If you are going to use
  -Memcached please use the pylibmc client library as python-memcached does
  +Memcached please use the `pylibmc` client library as `python-memcached` does
  not handle storing binary data correctly. If you use Redis, please install
  -`python-redis <https://pypi.python.org/pypi/redis>`.
  +the `redis <https://pypi.python.org/pypi/redis>`_ Python package: ::
  +
  + pip install redis
  For setting your timeouts, this is done in the Superset metadata and goes
  up the "timeout searchpath", from your slice configuration, to your
  