Add issue template with list of repos (#1971)

Author: natemcmaster

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,22 @@
+To address your issues more quickly, please open the issue in the most appropriate repository. These are some of the most common repos:
+
+Common ASP.NET and Entity Framework repos and projects:
+
+ - Documentation: https://github.com/aspnet/Docs
+ - MVC: https://github.com/aspnet/Mvc
+ - Entity Framework Core: https://github.com/aspnet/EntityFramework
+ - Entity Framework 6: https://github.com/aspnet/EntityFramework6
+ - SignalR: https://github.com/aspnet/SignalR
+ - ASP.NET Core in Docker: https://github.com/aspnet/aspnet-docker
+ - Microsoft.NET.Sdk.Web: https://github.com/aspnet/websdk
+ - Kestrel HTTP Server: https://github.com/aspnet/KestrelHttpServer
+ - ASP.NET Katana: https://github.com/aspnet/AspNetKatana
+ - and more! See a full list here: https://github.com/aspnet
+
+Other common projects:
+
+ - NuGet: https://github.com/NuGet/home
+ - .NET Core CLI, SDK, or runtime: https://github.com/dotnet/core
+ - Visual Studio: https://developercommunity.visualstudio.com
+ - Visual Studio Code: https://github.com/microsoft/vscode
+ - Omnisharp (C# support for VS Code): https://github.com/omnisharp/omnisharp-vscode