Add documents about controllers inherited from kubernetes.

Signed-off-by: RainbowMango <qdurenhongcai@gmail.com>

docs/userguide/configure-controllers.md

@@ -3,8 +3,13 @@
 **Table of Contents**  *generated with [DocToc](https://github.com/thlorenz/doctoc)*
 
 - [Configure Controllers](#configure-controllers)
-  - [Controllers Overview](#controllers-overview)
-  - [Configure Controllers](#configure-controllers-1)
+  - [Karmada Controllers](#karmada-controllers)
+    - [Configure Karmada Controllers](#configure-karmada-controllers)
+  - [Kubernetes Controllers](#kubernetes-controllers)
+    - [Recommended Controllers](#recommended-controllers)
+      - [namespace](#namespace)
+      - [garbagecollector](#garbagecollector)
+      - [serviceaccount-token](#serviceaccount-token)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -14,13 +19,13 @@ Karmada maintains a bunch of controllers which are control loops that watch the
 request changes where needed. Each controller tries to move the current state closer to the desired state.
 See [Kubernetes Controller Concepts][1] for more details.
 
-## Controllers Overview
+## Karmada Controllers
 
-The controllers are embedded into component of `karmada-controller-manager` or `karmada-agent` and will be launched  
+The controllers are embedded into components of `karmada-controller-manager` or `karmada-agent` and will be launched  
 along with components startup. Some controllers may be shared by `karmada-controller-manager` and `karmada-agent`.
 
 | Controller    | In karmada-controller-manager | In karmada-agent |
-|------------------|-------------------------------|-----------------|
+|---------------|-------------------------------|------------------|
 | cluster       | Y                             | N                |
 | clusterStatus | Y                             | Y                |
 | binding       | Y                             | N                |
@@ -33,7 +38,7 @@ along with components startup. Some controllers may be shared by `karmada-contro
 | unifiedAuth   | Y                             | N                |
 | hpa           | Y                             | N                |
 
-## Configure Controllers
+### Configure Karmada Controllers
 
 You can use `--controllers` flag to specify the enabled controller list for `karmada-controller-manager` and
 `karmada-agent`, or disable some of them in addition to the default list.
@@ -49,8 +54,45 @@ E.g. Disable some controllers:
 ```
 Use `-foo` to disable the controller named `foo`.
 
-> Note: The default controller list might be changed in the following release. The controllers enabled by last release
+> Note: The default controller list might be changed in the future releases. The controllers enabled in the last release
 > might be disabled or deprecated and new controllers might be introduced too. Users who are using this flag should
 > check the release notes before system upgrade.
 
+## Kubernetes Controllers
+
+In addition to the controllers that are maintained by the Karmada community, Karmada also requires some controllers from
+Kubernetes. These controllers run as part of `kube-controller-manager` and are maintained by the Kubernetes community.
+
+Users are recommended to deploy the `kube-controller-manager` along with Karmada components. And the installation
+methods list in [installation guide][2] would help you deploy it as well as Karmada components.
+
+### Recommended Controllers
+
+Not all controllers in `kube-controller-manager` are necessary for Karmada, if you are deploying
+Karmada using other tools, you might have to configure the controllers by `--controllers` flag just like what we did in
+[example of kube-controller-manager deployment][3].
+
+The following controllers are tested and recommended by Karmada.
+
+#### namespace
+TODO.
+
+#### garbagecollector
+TODO.
+
+#### serviceaccount-token
+
+The `serviceaccount-token` controller runs as part of `kube-controller-manager`.
+It watches `ServiceAccount` creation and creates a corresponding ServiceAccount token Secret to allow API access.
+
+For the Karmada control plane, after a `ServiceAccount` object is created by the administrator, we also need
+`serviceaccount-token` controller to generate the ServiceAccount token `Secret`, which will be a relief for
+administrator as he/she doesn't need to manually prepare the token.
+
+More details please refer to:
+- [service account token controller](https://kubernetes.io/docs/reference/access-authn-authz/service-accounts-admin/#token-controller)
+- [service account tokens](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#service-account-tokens)
+
 [1]: https://kubernetes.io/docs/concepts/architecture/controller/
+[2]: https://github.com/karmada-io/karmada/blob/master/docs/installation/installation.md
+[3]: https://github.com/karmada-io/karmada/blob/master/artifacts/deploy/kube-controller-manager.yaml