Make the origin of kubelet config explicit

Signed-off-by: Kotaro Inoue <[email protected]>

Author: musaprg

docs/book/src/tasks/bootstrap/kubeadm-bootstrap/kubelet-config.md

@@ -10,7 +10,7 @@ CAPBK has several ways to configure kubelet.
 
 You can use `KubeadmConfigSpec.files` to put any files on nodes. This example puts a `KubeletConfiguration` file on nodes via `KubeadmConfigSpec.files`, and makes kubelet use it via `KubeadmConfigSpec.kubeletExtraArgs`. You can check available configurations of `KubeletConfiguration` on [Kubelet Configuration (v1beta1) | Kubernetes](https://kubernetes.io/docs/reference/config-api/kubelet-config.v1beta1/#kubelet-config-k8s-io-v1beta1-KubeletConfiguration).
 
-This method is easy to replace the whole kubelet configuration, but it is not easy to replace only a part of the kubelet configuration.
+This method is easy to replace the whole kubelet configuration generated by kubeadm, but it is not easy to replace only a part of the kubelet configuration.
 
 ### KubeadmControlPlaneTemplate