---
upgrade:
  - |
    Improved the configuration of Ironic's pin_release_version setting by:

    - Dropping variable ``openstack_previous_release_name`` and replacing
      it with ``ironic_pin_release_version``
    - Making the setting optional by default
    - Adding proper documentation explaining when to use this setting

    See `documentation for pin_release_version <https://docs.openstack.org/ironic/latest/configuration/config.html#DEFAULT.pin_release_version>`_ for more details.