Update README.md

Author: Sunny-117

README.md

@@ -224,6 +224,7 @@ TODOS
 - [求集合单词组合起来的不同结果，集合中的单词不重复，每个结果包含所有单词](https://github.com/Sunny-117/js-challenges/issues/418)
 - [实现简易版的useState](https://github.com/Sunny-117/js-challenges/issues/502)
 - [数组乱序-百度实习](https://github.com/Sunny-117/js-challenges/issues/508)
+- [排序找第几个最大-快手实习](https://github.com/Sunny-117/js-challenges/issues/509)
 
 ## ts 类型体操