Improvement: Remove Heapster content from HPA. (#29547)

* Improvement: Remove Heapster content from HPA.

* Add more descriptive link for Metrics Server.

Author: Shubham82

content/en/docs/tasks/run-application/horizontal-pod-autoscale.md

@@ -68,14 +68,7 @@ or the custom metrics API (for all other metrics).
 
 The HorizontalPodAutoscaler normally fetches metrics from a series of aggregated APIs (`metrics.k8s.io`,
 `custom.metrics.k8s.io`, and `external.metrics.k8s.io`).  The `metrics.k8s.io` API is usually provided by
-metrics-server, which needs to be launched separately. See
-[metrics-server](/docs/tasks/debug-application-cluster/resource-metrics-pipeline/#metrics-server)
-for instructions. The HorizontalPodAutoscaler can also fetch metrics directly from Heapster.
-
-{{< note >}}
-{{< feature-state state="deprecated" for_k8s_version="v1.11" >}}
-Fetching metrics from Heapster is deprecated as of Kubernetes 1.11.
-{{< /note >}}
+metrics-server, which needs to be launched separately. For more information about resource metrics, see [Metrics Server](/docs/tasks/debug-application-cluster/resource-metrics-pipeline/#metrics-server).
 
 See [Support for metrics APIs](#support-for-metrics-apis) for more details.
 
@@ -344,8 +337,6 @@ APIs, cluster administrators must ensure that:
 
    * For external metrics, this is the `external.metrics.k8s.io` API.  It may be provided by the custom metrics adapters provided above.
 
-* The `--horizontal-pod-autoscaler-use-rest-clients` is `true` or unset.  Setting this to false switches to Heapster-based autoscaling, which is deprecated.
-
 For more information on these different metrics paths and how they differ please see the relevant design proposals for
 [the HPA V2](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/autoscaling/hpa-v2.md),
 [custom.metrics.k8s.io](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/custom-metrics-api.md)