Add APL-related items (#6652)

* Add one APL book

And fix links and notes the some others

* Add APL cheat sheets

* APL courses

* French APL video series

* mark APL Course as in process, add one more course

* mark as in process

* ADSP and Array Cast

* Add APL

* Add APL-related entries

* Add number for sort ordering

* correct number of blank lines between last section and next heading

* Remove trailing slash

* Move book

* Move book and limit URLs to 1 per line

* full URL

* add missing line

* Combine into playlist

* replace multiple links with single link

… which is a redirect to the listing for the latest released version

courses/free-courses-fr.md

@@ -1,6 +1,7 @@
 ### Index
 
 * [Algorithmes & Structures des données](#algorithmes)
+* [APL](#apl)
 * [Bash / Shell](#bash--shell)
 * [C](#c)
 * [C#](#c-sharp)
@@ -25,6 +26,11 @@
 * [Cours d'Algorithmie](https://www.youtube.com/playlist?list=PLrSOXFDHBtfGy7xYmf5LlNr8f-niDkf7_) - Formation Video
 
 
+### APL
+
+* [Découvrez le langage APL](https://www.youtube.com/watch?v=Nxq1BUUXobM&list=PLYKQVqyrAEj_DwkVAvj7xHxr72ite69nW) - Schraf : Maths-info
+
+
 ### Bash / Shell
 
 * [Apprendre à utiliser le shell Bash](https://www.pierre-giraud.com/shell-bash/) - Pierre Giraud