update maintenance.md for controller-tools update.
@@ -49,7 +49,7 @@ $ VERSION=<upgrading controller-runtime version>
$ go get sigs.k8s.io/controller-runtime@v${VERSION}
```
-Read the [kubebuilder go.mod](https://github.com/kubernetes-sigs/kubebuilder/blob/master/go.mod), and check the controller-tools version corresponding to controller-runtime.
+Read the [`controller-tools`'s release note](https://github.com/kubernetes-sigs/controller-tools/releases), and update to the newest version that is compatible with all supported kubernetes versions. If there are breaking changes, we should decide how to manage these changes.
Then, upgrade the controller-tools's version by the following commands.
```bash
