Add fields to dotnet new NuSpec file

Author: SteveSandersonMS

templates/package-builder/src/dotnetnew/Microsoft.AspNetCore.SpaTemplates.nuspec

@@ -8,6 +8,8 @@
         <language>en-US</language>
         <projectUrl>https://github.com/aspnet/javascriptservices</projectUrl>
         <licenseUrl>https://www.microsoft.com/web/webpi/eula/net_library_eula_enu.htm</licenseUrl>
+        <copyright>Copyright © Microsoft Corporation</copyright>
+        <requireLicenseAcceptance>true</requireLicenseAcceptance>
         <packageTypes>
             <packageType name="Template" />
         </packageTypes>