Fix pages that reference removed API groups

Quite some resources have been moved out of the `extensions` API group
since 1.18; the `apps/v1beta1` and `apps/v1beta2` group versions are
also dropped. This PR updates the pages which still reference such API
groups or group versions.

content/en/docs/tasks/access-application-cluster/ingress-minikube.md

@@ -132,7 +132,7 @@ The following file is an Ingress resource that sends traffic to your Service via
 
 1. Create `example-ingress.yaml` from the following file:
 
-        apiVersion: networking.k8s.io/v1beta1 # for versions before 1.14 use extensions/v1beta1
+        apiVersion: networking.k8s.io/v1beta1
         kind: Ingress
         metadata:
           name: example-ingress
@@ -243,7 +243,7 @@ The following file is an Ingress resource that sends traffic to your Service via
 
     Output: 
     ```shell
-    ingress.extensions/example-ingress configured
+    ingress.networking/example-ingress configured
     ```
 
 ## Test Your Ingress

content/en/docs/tasks/administer-cluster/dns-horizontal-autoscaling.md

@@ -160,7 +160,7 @@ kubectl scale deployment --replicas=0 dns-autoscaler --namespace=kube-system
 
 The output is:
 
-    deployment.extensions/dns-autoscaler scaled
+    deployment.apps/dns-autoscaler scaled
 
 Verify that the replica count is zero: