Add automated worker machine management section to docs tasks

Author: enxebre

docs/book/src/SUMMARY.md

@@ -11,10 +11,12 @@
     - [Kubeadm based bootstrap](./tasks/kubeadm-bootstrap.md)
     - [Upgrading management and workload clusters](./tasks/upgrading-clusters.md)
     - [Upgrading Cluster API components](./tasks/upgrading-cluster-api-versions.md)
-    - [Configure a MachineHealthCheck](./tasks/healthcheck.md)
     - [Kubeadm based control plane management](./tasks/kubeadm-control-plane.md)
     - [Updating Machine Infrastructure and Bootstrap Templates](tasks/updating-machine-templates.md)
-    - [Using the Cluster Autoscaler](./tasks/cluster-autoscaler.md)
+    - [Automated Machine management](./tasks/automated-machine-management/index.md)
+      - [Scaling](./tasks/automated-machine-management/scaling.md)
+      - [Auto scaling](./tasks/automated-machine-management/auto-scaling.md)
+      - [Health checking](./tasks/automated-machine-management/healthchecking.md)
     - [Experimental Features](./tasks/experimental-features/experimental-features.md)
         - [MachinePools](./tasks/experimental-features/machine-pools.md)
         - [ClusterResourceSet](./tasks/experimental-features/cluster-resource-set.md)

docs/book/src/tasks/cluster-autoscaler.md renamed to docs/book/src/tasks/automated-machine-management/auto-scaling.md

@@ -1,6 +1,6 @@
 # Using the Cluster Autoscaler
 
-Cluster Autoscaler is a tool that automatically adjusts the size of the Kubernetes cluster based
+This section applies only to worker Machines. Cluster Autoscaler is a tool that automatically adjusts the size of the Kubernetes cluster based
 on the utilization of Pods and Nodes in your cluster. For more general information about the
 Cluster Autoscaler, please see the
 [project documentation](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler).

docs/book/src/tasks/healthcheck.md renamed to docs/book/src/tasks/automated-machine-management/healthchecking.md

@@ -179,4 +179,4 @@ Before deploying a MachineHealthCheck, please familiarise yourself with the foll
 - If a Machine fails for any reason (if the FailureReason is set), the Machine will be remediated immediately
 
 <!-- links -->
-[management cluster]: ../reference/glossary.md#management-cluster
+[management cluster]: ../../reference/glossary.md#management-cluster

docs/book/src/tasks/automated-machine-management/index.md

@@ -0,0 +1,3 @@
+# Automated Machine management
+
+This section details some tasks related to automated Machine management.

docs/book/src/tasks/automated-machine-management/scaling.md

@@ -0,0 +1,13 @@
+# Scaling Nodes
+
+This section applies only to worker Machines. You can add or remove compute capacity for your cluster workloads by creating or removing Machines. A Machine expresses intent to have a Node with a defined form factor.
+
+Machines can be owned by scalable resources i.e. MachineSet and MachineDeployments.
+
+You can scale MachineSets and MachineDeployments in or out by expressing intent via `.spec.replicas or updating the scale subresource e.g `kubectl scale machinedeployment foo --replicas=5`.
+
+When you delete a Machine directly or by scaling down, the same process takes place in the same order:
+- The Node backed by that Machine will try to be drained indefinitely and will wait for any volume to be detached from the Node unless you specify a `.spec.nodeDrainTimeout`.
+  - CAPI uses default [kubectl draining implementation](https://kubernetes.io/docs/tasks/administer-cluster/safely-drain-node/) with `-–ignore-daemonsets=true`. If you needed to ensure DaemonSets eviction you'd need to do so manually by also adding proper taints to avoid rescheduling.
+- The infrastructure backing that Node will try to be deleted indefinitely.
+- Only when the infrastructure is gone, the Node will try to be deleted indefinitely unless you specify `.spec.nodeDeletionTimeout`.