Mention known issues while moving etcd to a different disk as part of day 2 activity.

Mention known issue while moving etcd to a different disk as part of day 2 activity.

   OCP 4.12 and above

    Easily

   1. Follow https://docs.openshift.com/container-platform/4.12/scalability_and_performance/recommended-performance-scale-practices/recommended-etcd-practices.html#move-etcd-different-disk_recommended-etcd-practices

  2. Delete a master node or recreate     

  Etcd db will be part of root mount and not secondary disk or the disk intended when the master node is recreated. Also the etcd mount will fail as the disk would not be formatted.

    We should warn users that recreating the master node will not create a separate /var/lib/etcd mount, manual intervention would be needed to follow the same steps. 

I can see there are lot of issues for recreating the master after day2 activity of moving etcd mount.
As when a master is recreated it will not honor the new etcd mount and it will continue to reside on root partition. 
Also to note, if we follow the last step mentioned in below document, it will fail for master node which is recreated, as it's secondary device will not be formatted as the previous service will not be present. The etcd mount file will exist though which would cause a can't boot failure.

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https://docs.openshift.com/container-platform/4.12/scalability_and_performance/recommended-performance-scale-practices/recommended-etcd-practices.html#move-etcd-different-disk_recommended-etcd-practices

        After the nodes are on a separate disk, update the etcd-mc.yml file with contents such as the following, replacing instances of <new_disk_name> with the noted device name: