Document couchdb disaster recovery process

[NOTE]: # ( ^^ Provide a general summary of the issue in the title above. ^^ )

## Description
i have a couchdb 3.1 cluster with 2 nodes VM and i backup daily data and etc folder
i would like to create, starting from backup same servers and data in a new environment (i would like to simulate a complete down on the old infrastructure)
i setup two couchdb, than i restore the 2 folder, than i change the ipaddress under vm.args
i add and remove the ip on the cluster to matching the actual configuration
https://docs.couchdb.org/en/stable/cluster/nodes.html#adding-a-node

in the interface i can see all the databases but are in status [This database failed to load.]
in the log file i have [Failed to ensure auth ddoc _users/_design/_auth exists for reason: read_failure]
if i try to browse _users/_design/_auth i receave
error "internal_server_error"
reason "No DB shards could be opened."
ref 2822102114

there is a step by step guide to do this?

[NOTE]: # ( Describe the problem you're encountering. )
[TIP]: # ( Do NOT give us access or passwords to your actual CouchDB! )

## Steps to Reproduce

[NOTE]: # ( Include commands to reproduce, if possible. curl is preferred. )

## Expected Behaviour
disaster solution for a cluster starting from backup

[NOTE]: # ( Tell us what you expected to happen. )

## Your Environment

[TIP]: # ( Include as many relevant details about your environment as possible. )
[TIP]: # ( You can paste the output of curl http://YOUR-COUCHDB:5984/ here. )

* CouchDB version used:3.1
* Browser name and version:
* Operating system and version:ubuntu 18

## Additional Context

[TIP]: # ( Add any other context about the problem here. )

Start with the CouchDB cluster node procedure at docs.couchdb.org/en/stable/cluster/nodes.html#adding-a-node and the reported backups of the data and etc folders. Trace how vm.args and node membership are changed in the replacement environment, then document a verified disaster-recovery sequence for a two-node CouchDB 3.1 cluster that avoids the reported shard and _users errors.

Written by the indexing model from the issue text.