Update README.md to fix the link for Part -1 for DFS + BFS Pattern

[ChampionTej05]

This PR removes the duplicate link for the BFS + DFS Pattern article Part 2 and adds correct Link from csgator's medium article.

Part 1: https://medium.com/leetcode-patterns/leetcode-pattern-1-bfs-dfs-25-of-the-problems-part-1-519450a84353 Part 2: https://medium.com/leetcode-patterns/leetcode-pattern-2-dfs-bfs-25-of-the-problems-part-2-a5b269597f52