Fix broken links in docs/README

Update GCE docs to reflect namespaces

update the output of kubectl get in examples/hazelcast

Replace REASON with STATUS in examples

Fixed link in persistent-volumes.md

update kubectl output in examples/elasticsearch

V0.21.0 merge to master

Add documentation for HA Kubernetes

This reverts commit aa9d423e.

Increase zero-limit pod RAM for spreading to 200 MB to match cluster

Change build/mark-new-version.sh to always create a backmerge branch

addon pods and represent less trivial fraction of typical machine RAM
(e.g. n1-standard-1).

Update UI redirect to kube-system.

AWS: Some images require volume mounts on /dev/xvdX

Update node info description in node.md

Change config files to kube-system which were missed in the original PR

De-dup, cleanup, overhaul networking docs

that reverts the doc diff.

This changes mark-new-version to create a backmerge branch that will
additionally handle the revert of the doc diff that's now created for
every release.

Sidebar: I really wish I knew a good git visualizer for GitHub - this
thing is going to start creating some awesome Gordian knots of merges.
(Or more like little Omegas, since they basically just change
version/base.go.)

Fixes #10825

AWS: Note about instance types

Align example in the client package with the api.

Check whether all nodes are healthy in e2e framework

Remove use of v1beta3 from ES logging

Fix service shell test