Extend the get av. zones seq diagram

```mermaid

sequenceDiagram

title Retrieve Edge Cloud Zones (i2Edge EdgeCloud Platform)

title Retrieve Edge Cloud Zones

actor AP as App Vertical Provider

participant CE as Capabilities Exposure

box Service Resource Manager

    participant SDK as EdgeCloudSDK

end

participant i2Edge

participant PiEdge

AP ->> CE: GET /edge-cloud-zones

CE ->> API: GET /av. zones

API ->> SDK: sdk.i2edge.get_zones()

SDK ->> i2Edge: GET /zones/list

API ->> SDK: sdk.piedge.get_zones()

SDK ->> PiEdge: GET /nodes

```

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