[en] Adding Operating System Book

free-programming-books.md

@@ -425,6 +425,7 @@
 
 
 ####Operating systems
+* [How to Make a Computer Operating System (Work in Progress)](https://github.com/SamyPesse/How-to-Make-a-Computer-Operating-System)
 * [The Art of Unix Programming](http://catb.org/esr/writings/taoup/html/) - Eric S. Raymond
 * [The Little Book of Semaphores](http://greenteapress.com/semaphores/) - Allen B. Downey
 * [Operating Systems and Middleware](https://gustavus.edu/mcs/max/os-book/) (PDF and LaTeX)