Document debian upgrade per data silos
We currently do this but it's not documented.
At first, we should have at least a rough plan to follow through.
This will allow:
- to add changes more easily
- new people to be able to take care of it too
- ease appropriation of the various part of the infra
Plan:
- swh/devel/swh-docs!455 (merged): rancher
- swh/devel/swh-docs!461 (merged): elasticsearch
- swh/devel/swh-docs!462 (merged): kafka
- swh/devel/swh-docs!464 (merged): cassandra
- postgresql
- proxmox
- winery/cea infra