Upgrading from CAPMVM 0.4.0 to 0.7.0 requires updates to the cluster objects

**What happened:**
I did update to flintlock v0.2.0 and capmvm v0.7.0 from capmvm v0.4.0

The schema did change in a few places and updates to my existing cluster templates and cluster objects in git were required.

From the single sshPublicKey to sshPublicKeys. I used these commands :

1. Remove lutz@dellbook on separate lines
`
$ sed -i 's/^ *lutz@dellbook//' clusters/management/clusters/*.yaml
`
2. Match & replace sshPublicKey with sshPublicKeys
`
$ sed -i -e 's/^ sshPublicKey: \(.*\)/ sshPublicKeys:\n - user: root\n authorizedKeys:\n - \1/' clusters/management/clusters/*.yaml
`
3. Remove mountpoint entries for the rootVolumes
`
$ sed -i '/^ *mountPoint:/d' ~/git/demo3-repo/clusters/management/clusters/*.yaml
`
Updating CAPI templates :
1. sshPublicKeys
`
$ sed -i -e 's/^ sshPublicKey: \(.*\)/ sshPublicKeys:\n - user: root\n authorizedKeys:\n - \1/' capmvm-*.yaml
`
2. Provider-id
`
$ sed -i 's#provider-id:.*#provider-id: "microvm://{{ ds.meta_data.vm_host }}/{{ ds.meta_data.instance_id }}"#' capmvm-*.yaml
`
3. Mountpoint issue
`
$ sed -i '/^ *mountPoint:/d'
`

It might be helpful for others that face the same situation.

Review the migration steps and YAML paths described for clusters/management/clusters/*.yaml and capmvm-*.yaml. First determine where upgrade guidance belongs in the repository; done would be a documented path from CAPMVM 0.4.0 to 0.7.0 covering the listed schema updates.

Written by the indexing model from the issue text.