Add Vue Essential Cheat sheet (#3735)

Co-authored-by: Yehezkiel Gunawan <yehezkiel.gunawan@codify.id>

free-programming-books.md

@@ -1783,6 +1783,7 @@ Kerridge (PDF) (email address *requested*, not required)
 #### Vue.js
 
 * [Learning Vue.js](https://riptutorial.com/Download/vue-js.pdf) (PDF)
+* [Vue Essential Cheatsheet](https://www.vuemastery.com/pdf/Vue-Essentials-Cheat-Sheet.pdf) (PDF)
 
 
 ### Jenkins