Update changelog for v1.2.1

CHANGELOG/CHANGELOG-1.2.md

@@ -13,9 +13,11 @@ Changelog for the K8ssandra Operator, new PRs should update the `unreleased` sec
 
 When cutting a new release, update the `unreleased` heading to the tag being generated and date, like `## vX.Y.Z - YYYY-MM-DD` and create a new placeholder section for  `unreleased` entries.
 
-## unreleased
+## v1.2.1 - 2022-09-13
 
 * [BUGFIX] [#675](https://github.com/k8ssandra/k8ssandra-operator/issues/675) K8ssandra is ignoring capital letters in the clusterName
+* [BUGFIX] [#641](https://github.com/k8ssandra/k8ssandra-operator/issues/641) Reaper ServiceMonitor is not properly configured
+* [BUGFIX] [#640](https://github.com/k8ssandra/k8ssandra-operator/issues/640) Fix NPEs when authentication is disabled
 * [BUGFIX] [#567](https://github.com/k8ssandra/k8ssandra-operator/issues/567) Fix no seeds error when all the Cassandra pods of a DC get restarted at once
 
 ## v1.2.0 - 2022-07-22