update docker image to docker hub (#3)

Author: Summer

content/dotnet-template-azure-iot-edge-module/CSharp/edgeConfiguration.json

@@ -14,7 +14,7 @@
           "edgeAgent": {
             "type": "docker",
             "settings": {
-              "image": "edgepreview.azurecr.io/azureiotedge/edge-agent:1.0-preview",
+              "image": "microsoft/azureiotedge-agent:1.0-preview",
               "createOptions": ""
             }
           },
@@ -23,7 +23,7 @@
             "status": "running",
             "restartPolicy": "always",
             "settings": {
-              "image": "edgepreview.azurecr.io/azureiotedge/edge-hub:1.0-preview",
+              "image": "microsoft/azureiotedge-hub:1.0-preview",
               "createOptions": ""
             }
           }