recover-control-plane.md

* ignore_unreachable for etcd dir cleanup

ignore_errors ignores errors occur within "file" module. However, when
the target node is offline, the playbook will still fail at this task
with node "unreachable" state. Setting "ignore_unreachable: true" allows
the playbook to bypass offline nodes and move on to proceed recovery
tasks on remaining online nodes.

* Re-arrange control plane recovery runbook steps

* Remove suggestion to manually update IP addresses

The suggestion was added in 48a18284 4
years ago. But a new task added 2 years ago, in
ee0f1e9d, automatically update API
server arg with updated etcd node ip addresses. This suggestion is no
longer needed.