Add Windows 1809 support

result/dotnet/Dockerfile.1809

@@ -0,0 +1,16 @@
+FROM  microsoft/dotnet:2.1-sdk-nanoserver-1809 as builder
+
+WORKDIR /Result
+COPY Result/Result.csproj .
+RUN dotnet restore
+
+COPY /Result .
+RUN dotnet publish -c Release -o /out Result.csproj
+
+# app image
+FROM microsoft/dotnet:2.1-aspnetcore-runtime-nanoserver-1809
+
+WORKDIR /app
+ENTRYPOINT ["dotnet", "Result.dll"]
+
+COPY --from=builder /out .