Update changelog for v3.22.0 release
## Unreleased
+## 3.22.0 (October 21, 2022)
+
Important Note -- This release changes the Provider default to enable Server-Side Apply mode. This change is
backward compatible, and should not require further action from users. The `enableServerSideApply` flag is
still present, so you may explicitly opt out if you run into any problems. This flag will be removed in the
