Update free-programming-books-langs.md (#7703)

* Update free-programming-books-langs.md

Added Q# lanaguge used for developing quantum algorithms on Azure

* Update free-programming-books-langs.md

Changed referencing of Q# to avoid the conflict of # symbol

* Update free-courses-en.md

Added class central

books/free-programming-books-langs.md

@@ -172,6 +172,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
     * [Pandas](#pandas)
     * [Pyramid](#pyramid)
     * [Tornado](#tornado)
+* [Q#](#q-sharp)
 * [QML](#qml)
 * [R](#r)
 * [Racket](#racket)
@@ -2029,6 +2030,11 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Learn Web Programming](https://bitbucket.org/hrojas/learn-web-programming)
 
 
+### <a id="q-sharp"></a>Q\#
+
+* [The Q# quantum programming language user guide](https://learn.microsoft.com/en-us/azure/quantum/user-guide) (HTML)
+
+
 ### QML
 
 * [Qt5 Cadaques](http://qmlbook.github.io) - Juergen Bocklage-Ryannel, Johan Thelin (HTML, PDF, ePub) (:construction: *in process*)

courses/free-courses-en.md

@@ -93,6 +93,7 @@
 
 ### 0 - MOOC
 
+* [class central](https://www.classcentral.com)
 * [Codecademy](https://www.codecademy.com)
 * [Coursera](https://www.coursera.org)
 * [Datacamp](https://www.datacamp.com)