update README.md to give out more information about the repo.

Given an array A of random integers and an integer k, find and return the kth largest element in the array.
Try to do this question in less than O(nlogn) time.
Input Format :

Line 1 : An integer N i.e. size of the array
Line 2 : N integers which are elements of the array, separated by spaces
Line 3 : An integer k

Output Format :

kth largest element

Input Constraints :
1 <= N, Ai,