add learning GNOME Korean book (#5852)

add learning GNOME(그놈배우기) Korean book

books/free-programming-books-ko.md

@@ -103,6 +103,7 @@
 ### Linux
 
 * [리눅스 서버를 다루는 기술](https://thebook.io/006718/)
+* [GNOME 배우기](https://sites.google.com/site/gnomekr/home/learning_gnome)
 
 
 ### Perl