[cli-reference] remove unnecessary subcommand list for freezer
[cli-reference] remove unnecessary subcommand list for freezer

At now, python-freezerclient provides a standard command completion.
Therefore, no need to maintain the static subcommand list.

Change-Id: If1dffcb57888e52949bf0814d56f75eda7f2958e

openstack/openstack-doc-tools,openstack/openstack-doc-tools