updating image location (#1486)

the image location has changed. the old location no longer exists. I found this issue when referring to instructions on how to deploy a sample application here: https://learn.microsoft.com/en-us/azure/application-gateway/tutorial-ingress-controller-add-on-existing#deploy-a-sample-application-using-agic

the results can be verified using the following commands:
# non-working location - 
docker pull mcr.microsoft.com/dotnet/core/samples:aspnetapp

# working location - 
docker pull mcr.microsoft.com/dotnet/samples:aspnetapp

Author: msfttklingenberg

docs/examples/aspnetapp.yaml

@@ -6,7 +6,7 @@ metadata:
     app: aspnetapp
 spec:
   containers:
-  - image: "mcr.microsoft.com/dotnet/core/samples:aspnetapp"
+  - image: "mcr.microsoft.com/dotnet/samples:aspnetapp"
     name: aspnetapp-image
     ports:
     - containerPort: 80