Patch 1 (EbookFoundation#6860)

* Update in C# free-programing books

I added some books that are in the microsoft documentation

* Put in alphabetical order

Author: JPAlfa

books/free-programming-books-langs.md

@@ -467,6 +467,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 
 ### <a id="csharp"></a>C\#
 
+* [Architect Modern Web Applications with ASP.NET Core and Azure](https://docs.microsoft.com/en-us/dotnet/architecture/modern-web-apps-azure/) - Steve "ardalis" Smith
 * [C# Notes for Professionals](http://goalkicker.com/CSharpBook/) - Compiled from StackOverflow documentation (PDF)
 * [C# Programming](https://en.wikibooks.org/wiki/C_Sharp_Programming) - Wikibooks
 * [C# Programming Yellow Book](https://www.robmiles.com/s/CSharp-Book-2019-Refresh.pdf) - Rob Miles (PDF) (2019)
@@ -481,8 +482,11 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Introduction to Rx](http://www.introtorx.com)
 * [Learn C# in Y Minutes](https://learnxinyminutes.com/docs/csharp/)
 * [Mastering Xamarin UI Development, Second Edition](https://www.packtpub.com/free-ebook/mastering-xamarin-ui-development-second-edition/9781788995511) - Steven F. Daniel (Packt account *required*)
+* [Modernize existing .NET applications with Azure cloud and Windows Containers](https://docs.microsoft.com/en-us/dotnet/architecture/modernize-with-azure-containers/) - Cesar de la Torre 
+* [Modernizing Desktop Apps on Windows with .NET 6](https://docs.microsoft.com/en-us/dotnet/architecture/modernize-desktop) - Olia Gavrysh, Miguel Angel Castejón Dominguez
 * [.NET Book Zero](http://www.charlespetzold.com/dotnet) - Charles Petzold (PDF, XPS)
 * [.NET Microservices: Architecture for Containerized .NET Applications](https://dotnet.microsoft.com/download/e-book/microservices-architecture/pdf) - Cesar de la Torre, Bill Wagner, Mike Rousos (PDF)
+* [Porting Existing ASP.NET Apps to .NET 6](https://docs.microsoft.com/en-us/dotnet/architecture/porting-existing-aspnet-apps/) - Steve "ardalis" Smith
 * [Threading in C#](http://www.albahari.com/threading/)
 * [Xamarin.Forms for macOS Succinctly](https://www.syncfusion.com/ebooks/xamarin_forms_for_mac_os_succinctly) - Alessandro Del Sole
 * [Xamarin.Forms Succinctly](https://www.syncfusion.com/ebooks/xamarin-forms-succinctly) - Alessandro Del Sole