docs: multiple docs can be added (etcd, ceph backups; ceph administration; networking)

[andy108369]

Backups (etcd, ceph)

Providers should ideally perform backups of the following data routinely:

• /var/lib/rook - rook cluster data (mgr + monitors) since monitors are typically fixed by a specific node via nodeSelector in their deployments;
• etcd backup - export $(grep -v '^#' /etc/etcd.env | xargs -d '\n'); etcdctl snapshot save etcd.backup - this can help one restore the K8s cluster config;

K8s cluster administration

It is all primarily in https://github.com/kubernetes-sigs/kubespray/blob/v2.21.0/docs/nodes.md ; I think we already have a link there from our docs;

Ceph (persistent storage) administration

• How to scale down & up the cluster (add hosts / disks (OSDs));
• How to recover Ceph from a failure (disk failure; and service recovery procedure);
• How to enable Ceph dashboard;
• How to tear down Ceph;

Notes for myself/internal: https://github.com/ovrclk/engineering/wiki/Ceph

Network / DNS config & verification

#80

[troian]

lets split it into multiple issues

1. docs: provider instructions on backup routines for etcd
2. ... ceph