add note about kube-rbac-proxy

Author: ebiiim

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## What comes next?
+
+- Upgrade `kubebuilder`.
+  - NOTE: We use `kube-rbac-proxy:v0.13.0` so [`gcr.io` retirement](https://github.com/kubernetes-sigs/kubebuilder/discussions/3907) affects us. The workaround is to use other image registry.
+
 ## 0.2.1 - 2023-01-05
 
 ### Changed

README.md

@@ -167,7 +167,7 @@ kubectl delete -f https://github.com/ebiiim/gitbackup/releases/download/v0.2.1/g
 
 ## Developing
 
-This Operator uses [Kubebuilder](https://github.com/kubernetes-sigs/kubebuilder), so we basically follow the Kubebuilder way. See the [Kubebuilder Documentation](https://book.kubebuilder.io/introduction.html) for details.
+This Operator uses [Kubebuilder](https://github.com/kubernetes-sigs/kubebuilder) (v3.8.0), so we basically follow the Kubebuilder way. See the [Kubebuilder Documentation](https://book.kubebuilder.io/introduction.html) for details.
 
 ### Prerequisites