Merge pull request #9758 from rifelpet/cert-known-issue

Add the client cert / ACM cert known issue to the 1.18 release notes

docs/releases/1.18-NOTES.md

@@ -113,6 +113,10 @@
 * If a custom Kops build was used on a cluster, a kops-controller Deployment may have been created that should get deleted.
   Run `kubectl -n kube-system delete deployment kops-controller` after upgrading to Kops 1.16.0-beta.1 or later.
 
+# Known Issues
+
+* AWS clusters with an ACM certificate attached to the API ELB (the cluster's `spec.api.loadBalancer.sslCertificate` is set) will need to reenable basic auth to use the kubeconfig context created by `kops export kubecfg`. Set `spec.kubeAPIServer.disableBasicAuth: false` before running `kops export kubecfg`. See [#9756](https://github.com/kubernetes/kops/issues/9756) for more information.
+
 # Deprecations
 
 * Support for Kubernetes versions 1.9 and 1.10 are deprecated and will be removed in kops 1.19.