add modern javascript cheatsheet (#6078)

more/free-programming-cheatsheets.md

@@ -111,6 +111,7 @@
 * [JavaScript CheatSheet](https://htmlcheatsheet.com/js/) (HTML)
 * [JavaScript Regex Cheatsheet](https://www.debuggex.com/cheatsheet/regex/javascript) - Debuggex (HTML)
 * [JavaScript WorldWide Cheatsheet](https://cheatography.com/davechild/cheat-sheets/javascript/) - Cheatography (JavaScript)
+* [Modern JavaScript Cheatsheet](https://github.com/mbeaudru/modern-js-cheatsheet) (HTML)
 
 
 #### jQuery