Merge pull request #242 from dlepow/patch-1

Update Dockerfile with MCR image

Author: PatAltimore

blockchain-workbench/auth-samples/netcore/Dockerfile

@@ -1,4 +1,4 @@
-FROM microsoft/dotnet:2.2-sdk
+FROM mcr.microsoft.com/dotnet/core/sdk:2.2
 
 WORKDIR /app
 
@@ -9,4 +9,4 @@ COPY . .
 RUN dotnet build --configuration release
 RUN dotnet publish --configuration release --output /app
 
-CMD ["dotnet", "/app/sample.dll"]
+CMD ["dotnet", "/app/sample.dll"]