Fixed missing trailing parenthesis in docs/releases/1.7.txt

  that doesn't use the cache system at all but instead a JSON file called

  ``staticfiles.json`` for storing the mapping between the original file name

  (e.g. ``css/styles.css``) and the hashed file name (e.g.

  ``css/styles.55e7cbb9ba48.css``. The ``staticfiles.json`` file is created

  ``css/styles.55e7cbb9ba48.css``). The ``staticfiles.json`` file is created

  when running the :djadmin:`collectstatic` management command and should

  be a less expensive alternative for remote storages such as Amazon S3.