Add 'Learn PowerShell in Y Minutes' (#3832)

* Add 'Learn PowerShell in Y Minutes'

* Add 'Learn C# in Y Minutes'

free-programming-books.md

@@ -1047,6 +1047,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Fundamentals of Computer Programming with C#](http://www.introprogramming.info/english-intro-csharp-book/read-online/) - Svetlin Nakov
 * [High level asynchronous programming with Reactive Extensions](https://github.com/petroemil/Rx.Book) - Emil Petro
 * [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-ebooks/mastering-xamarin-ui-development-second-edition) - Steven F. Daniel (Packt account *required*)
 * [Object Oriented Programming using C#](http://bookboon.com/en/object-oriented-programming-using-c-sharp-ebook) - Simon Kendal, Bookboon. (email address *requested*, not required)
 * [Threading in C#](http://www.albahari.com/threading/)
@@ -2171,6 +2172,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Introduction to PowerShell for Unix People](https://www.gitbook.com/book/devopscollective/a-unix-person-s-guide-to-powershell/details) (PDF, ePub, HTML)
 * [Layman’s Guide to PowerShell 2.0 remoting](http://www.ravichaganti.com//blog/wp-content/uploads/2010/12/A%20layman's%20guide%20to%20PowerShell%202.0%20remoting-v2.pdf) (PDF)
 * [Learn PowerShell Core 6.0](https://www.packtpub.com/free-ebooks/learn-powershell-core-60) - David das Neves, Jan-Hendrik Peters (Packt account *required*)
+* [Learn PowerShell in Y Minutes](https://learnxinyminutes.com/docs/powershell/)
 * [Mastering PowerShell v2](http://community.idera.com/powershell/powertips/b/ebookv2#pi619PostSortOrder=Ascending)
 * [PowerShell 2.0 – One CMDLET At A Time](http://www.jonathanmedd.net/wp-content/uploads/2010/09/PowerShell_2_One_Cmdlet_at_a_Time.pdf) (PDF)
 * [PowerShell Notes for Professionals](http://books.goalkicker.com/PowerShellBook/) - Compiled from StackOverflow documentation (3.x)