add copyright statements

Author: JialinXin

samples/ServerSideBlazor/ChatClient.cs

@@ -1,7 +1,9 @@
-using Microsoft.JSInterop;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.JSInterop;
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 
 namespace ServerSideBlazor

samples/ServerSideBlazor/Hubs/ChatHub.cs renamed to samples/ServerSideBlazor/Hub/ChatHub.cs

@@ -1,10 +1,12 @@
-using Microsoft.AspNetCore.SignalR;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.AspNetCore.SignalR;
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 
-namespace ServerSideBlazor.Hubs
+namespace ServerSideBlazor
 {
     /// <summary>
     /// The SignalR hub 

samples/ServerSideBlazor/Startup.cs

@@ -1,3 +1,6 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -55,7 +58,7 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
                 endpoints.MapBlazorHub();
                 endpoints.MapFallbackToPage("/_Host");
                 endpoints.MapDefaultControllerRoute();
-                endpoints.MapHub<Hubs.ChatHub>("/chathub");
+                endpoints.MapHub<ChatHub>("/chathub");
             });
         }
     }