Link from kubeadm mention of RBAC to authz docs

Co-authored-by: Qiming Teng <[email protected]>

Author: Tim Bannister

content/en/docs/tasks/administer-cluster/kubeadm/kubeadm-certs.md

@@ -326,7 +326,8 @@ CSRs requesting serving certificates for any IP or domain name.
 During cluster creation, kubeadm signs the certificate in the `admin.conf` to have
 `Subject: O = system:masters, CN = kubernetes-admin`.
 [`system:masters`](/docs/reference/access-authn-authz/rbac/#user-facing-roles)
-is a break-glass, super user group that bypasses the authorization layer (e.g. RBAC).
+is a break-glass, super user group that bypasses the authorization layer (for example,
+[RBAC](/docs/reference/access-authn-authz/authorization/rbac/)).
 Sharing the `admin.conf` with additional users is **not recommended**!
 
 Instead, you can use the [`kubeadm kubeconfig user`](/docs/reference/setup-tools/kubeadm/kubeadm-kubeconfig)