update readme.md

Author: bestgopher

README.md

@@ -3,11 +3,12 @@ leetcode by rust
 
 ### 题目
 
-- [746. 使用最小花费爬楼梯]
+-  746：使用最小花费爬楼梯
 	- [src](https://github.com/rustors/leetcode/blob/main/src/bin/check-if-n-and-its-double-exist.rs) 
 	- [leetcode](https://leetcode-cn.com/problems/check-if-n-and-its-double-exist/)
 
 - 1008：前序遍历构造二叉搜索树
-- [src](https://github.com/rustors/leetcode/blob/main/src/bin/construct-binary-search-tree-from-preorder-traversal.rs)
+
+	- [src](https://github.com/rustors/leetcode/blob/main/src/bin/construct-binary-search-tree-from-preorder-traversal.rs)
 	- [leetcode](https://leetcode-cn.com/problems/construct-binary-search-tree-from-preorder-traversal/)