[doc] Issue in "Management cluster definition file"

[peteingithub]

Management cluster definition file:

https://suse-edge.github.io/atip-management-cluster.html#mgmt-cluster-image-definition-file

Add longhorn.yaml values to set replica size to 1 like Rancher and NeuVector does.

persistence:
  defaultClassReplicaCount: 1

csi:
  attacherReplicaCount: 1
  provisionerReplicaCount: 1
  resizerReplicaCount: 1
  snapshotterReplicaCount: 1

defaultSettings:
  defaultReplicaCount: 1

longhornUI:
  replicas: 1

How about endpoint-copier-operator?

[agracey]

I think we actually want to keep the storage as HA so we don't get data loss. Unsure about endpoint copier... @alknopfler?

[agracey]

That said, the UI could be scaled down.