Added Scratch book. Added authors to a couple existing Scratch books (#9044)

* Added Scratch book.  Added authors to a couple existing Scratch books

* Added Scratch book.  Added authors to a couple existing Scratch books.  Fixed missing PDF indicators.

* Update books/free-programming-books-langs.md

Co-authored-by: Sharan J <50091666+shrn01@users.noreply.github.com>

Co-authored-by: Sharan J <50091666+shrn01@users.noreply.github.com>

books/free-programming-books-langs.md

@@ -2308,10 +2308,11 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 
 ### Scratch
 
-* [An Introductory Computing Curriculum Using Scratch](http://scratched.gse.harvard.edu/guide/download.html)
-* [Computer Science Concepts in Scratch](https://stwww1.weizmann.ac.il/scratch/scratch_en/)
+* [An Introductory Computing Curriculum Using Scratch](http://scratched.gse.harvard.edu/guide/download.html) (HTML)
+* [Code Club Book of Scratch](https://magpi.raspberrypi.com/books/book-of-scratch) - Rik Cross, Tracy Gardner (PDF)
+* [Computer Science Concepts in Scratch](https://stwww1.weizmann.ac.il/scratch/scratch_en/) - Michal Armoni, Moti Ben-Ari (PDF)
 * [Learn to Code with Scratch](https://magpi.raspberrypi.com/books/essentials-scratch-v1) - The MagPi magazine (PDF)
-* [Scratch Programming Playground](https://inventwithscratch.com/book/) - Al Sweigart
+* [Scratch Programming Playground](https://inventwithscratch.com/book/) - Al Sweigart (HTML)
 
 
 ### Sed