review: split the CTB FG info for KAS and KCM

Author: stlaz

content/en/docs/reference/command-line-tools-reference/feature-gates/cluster-trust-bundle.md

@@ -10,9 +10,14 @@ stages:
     defaultValue: false
     fromVersion: "1.27"
 ---
-Enable ClusterTrustBundle support, including kubelet integration. Also makes the Kubernetes
-controller manager publish a ClusterTrustBundle for the `kubernetes.io/kube-apiserver-serving`
-signer.
+This feature gate exists in the Kubernetes API server and the controller manager.
+
+Used from the kube-apiserver, it enables ClusterTrustBundle support, including kubelet integration
+via the ClusterTrustBundle projected volumes API.
+
 In order to use the ClusterTrustBundle API in your cluster, you need to enable this feature gate
 and also [enable](/docs/tasks/administer-cluster/enable-disable-api/) the associated alpha API group
-using the `--runtime-config` command line argument to kube-apiserver.
+using the `--runtime-config` command line argument to kube-apiserver.
+
+In the Kubernetes controller manager, it is used to control publishing of a ClusterTrustBundle
+for the `kubernetes.io/kube-apiserver-serving` signer.