update readme

:

Author: libterty

README.md

@@ -6,4 +6,4 @@
     -   Day 3: [Ransom Note](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-three/index.ts) :hushed:
     -   Day 4: [Number Complement](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-four/index.ts) :laughing:
     -   Day 5: [First Unique Character in a String](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-five/index.ts) :smirk:
-    -   Day 6: [First Unique Character in a String](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-six/index.ts) :relaxed:
+    -   Day 6: [Majority Element](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-six/index.ts) :relaxed: