Merge pull request #2 from xamarin/dev/therzok/dotnet5-feed

Author: Therzok

NuGet.config

@@ -28,6 +28,7 @@
     <add key="aspnet-extensions" value="https://dotnetfeed.blob.core.windows.net/aspnet-extensions/index.json" />
     <add key="gRPC repository" value="https://grpc.jfrog.io/grpc/api/nuget/v3/grpc-nuget-dev" />
     <add key="dotnet-tools" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json" />
+    <add key="dotnet5" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json" />
   </packageSources>
   <disabledPackageSources>
     <clear />