Add config API for kube-controller-manager configuration

Author: tengqm

content/en/docs/reference/_index.md

@@ -89,6 +89,7 @@ operator to use or manage a cluster.
 * [kube-scheduler configuration (v1beta2)](/docs/reference/config-api/kube-scheduler-config.v1beta2/),
   [kube-scheduler configuration (v1beta3)](/docs/reference/config-api/kube-scheduler-config.v1beta3/) and
   [kube-scheduler configuration (v1)](/docs/reference/config-api/kube-scheduler-config.v1/)
+* [kube-controller-manager configuration (v1alpha1)](/docs/reference/config-api/kube-controller-manager-config.v1alpha1/)
 * [kube-proxy configuration (v1alpha1)](/docs/reference/config-api/kube-proxy-config.v1alpha1/)
 * [`audit.k8s.io/v1` API](/docs/reference/config-api/apiserver-audit.v1/)
 * [Client authentication API (v1beta1)](/docs/reference/config-api/client-authentication.v1beta1/) and