Add Schema to Arduibo Serial Sample: RootPnpBridgeISerialPnPnterfaceModel.json

[djaus2]

{ "@id": "dtmi:contoso:com:serialpnp;1", "@type": "Interface", "displayName": "Pnp Bridge Root Interface Model serialpnp1", "name": "serialpnp1", "contents": [ { "@type": [ "Telemetry", "Temperature" ], "description": "Current temperature on the device", "displayName": "Temperature", "name": "temp", "schema": "double", "unit": "degreeFahrenheit" } ], "@context": "dtmi:dtdl:context;2" }