Fix templates directory structure to produce correct nupkg output

templates/Microsoft.DotNet.Web.Spa.ProjectTemplates/react/Program.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+
+namespace ReactSpa
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            BuildWebHost(args).Run();
+        }
+
+        public static IWebHost BuildWebHost(string[] args) =>
+            WebHost.CreateDefaultBuilder(args)
+                .UseStartup<Startup>()
+                .Build();
+    }
+}