Fix relative links issue in English content (#13307)

* `http://kubernetes.io/docs/` -> `/docs/` in content/en folder

* `https://kubernetes.io/docs/` -> `/docs/` in content/en folder

content/en/docs/reference/setup-tools/kubeadm/generated/kubeadm_token.md

@@ -20,7 +20,7 @@ What is a bootstrap token more exactly?
  - The name of the Secret must be named "bootstrap-token-(token-id)".
 
 You can read more about bootstrap tokens here:
-  https://kubernetes.io/docs/admin/bootstrap-tokens/
+  /docs/admin/bootstrap-tokens/
 
 
 ```
@@ -80,6 +80,3 @@ kubeadm token [flags]
 
   </tbody>
 </table>
-
-
-

content/en/docs/reference/setup-tools/kubeadm/kubeadm-init.md

@@ -283,7 +283,7 @@ In order to set up a cluster where the master and worker nodes communicate with
 ### Setting the node name
 
 By default, `kubeadm` assigns a node name based on a machine's host address. You can override this setting with the `--node-name`flag.
-The flag passes the appropriate [`--hostname-override`](https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/#options) 
+The flag passes the appropriate [`--hostname-override`](/docs/reference/command-line-tools-reference/kubelet/#options) 
 to the kubelet.
 
 Be aware that overriding the hostname can [interfere with cloud providers](https://github.com/kubernetes/website/pull/8873).
@@ -311,7 +311,7 @@ without manual intervention. This and other limitations are expected to be
 resolved before self-hosting graduates from alpha.
 
 By default, self-hosted control plane Pods rely on credentials loaded from
-[`hostPath`](https://kubernetes.io/docs/concepts/storage/volumes/#hostpath)
+[`hostPath`](/docs/concepts/storage/volumes/#hostpath)
 volumes. Except for initial creation, these credentials are not managed by
 kubeadm.