A network engineer is using Ansible to manage a fleet of Cisco IOS XE devices. The playbook uses the 'ios_config' module to push a set of configuration lines. After running the playbook, the engineer notices that the configuration changes are not being saved to the startup configuration, and the devices revert to the previous configuration after a reboot. Which parameter should be added to the 'ios_config' task to ensure the running configuration is saved to the startup configuration?