Update index.md

Author: ratulb

docs/index.md

@@ -2,6 +2,6 @@
 - [Game of life](game_of_life.md) ➔
  Contains an implementation of [Conway's Game of Life](https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life) cellular automation.
 - [Two sum](two_sum.md) ➔ Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
-- [ Buy and Sell Stock](buy_and_sell_stock.md) ➔ Maximize profit by buying once and selling later on a future day.
+- [ Buy and Sell Stock 1](buy_and_sell_stock.md) ➔ Maximize profit by buying once and selling later on a future day.