Upgrading from v0.21.0 to v0.22.0 is straightforward, and only requires updating your dittofeed image tag.
If you are on a version of dittofeed prior to v0.20.0, you will need to upgrade to v0.20.0 prior to upgrading to v0.22.0. See the Upgrading from v0.19.0 to v0.20.0 guide for more information on upgrading to v0.20.0.