* add ES6 example for binary search
* add ES6 example for selection sort
* add ES6 example for countdown
* add ES6 example for greet
* add ES6 example for factorial
* edit ES6 example for quicksort
* add ES6 example for loop sum
* add ES6 example for recursive sum
* add ES6 example for recursive count
* add ES6 example for recursive max
* add ES6 example for price of groceries
* add ES6 example for check voter
* add ES6 example for breadth-first search
* add ES6 example for dijkstras algorithm
* edit ES6 example for dijkstras algorithm
* edit ES6 example for set covering
* add ES6 example for longest common subsequence
