docs: update readme documents

Author: yanglbme

README.md

@@ -168,7 +168,11 @@
 - [子集](/solution/0000-0099/0078.Subsets/README.md)
 - [子集 II](/solution/0000-0099/0090.Subsets%20II/README.md)
 
-### 混合问题
+### 设计
+
+- [实现 Trie (前缀树)](/solution/0200-0299/0208.Implement%20Trie%20%28Prefix%20Tree%29/README.md)
+- [设计哈希集合](/solution/0700-0799/0705.Design%20HashSet/README.md)
+- [设计哈希映射](/solution/0700-0799/0706.Design%20HashMap/README.md)
 
 ### 数据库
 
@@ -204,8 +208,6 @@
 
 非常感谢以下所有朋友对本项目的贡献，你们是最可爱的人！
 
-<!-- https://opencollective.com/doocs-leetcode/contributors.svg?width=890&button=false -->
-
 <a href="https://github.com/doocs/leetcode/graphs/contributors" target="_blank"><img src="./images/contributors.svg" /></a>
 
 ## 赞助者

README_EN.md

@@ -161,7 +161,13 @@ Complete solutions to [LeetCode](https://leetcode-cn.com/problemset/all/), [LCOF
 - [Subsets](/solution/0000-0099/0078.Subsets/README_EN.md)
 - [Subsets II](/solution/0000-0099/0090.Subsets%20II/README_EN.md)
 
-### Misc
+### Design
+
+- [Implement Trie (Prefix Tree)](<solution/0200-0299/0208.Implement%20Trie%20(Prefix%20Tree)/README_EN.md>)
+- [Design HashSet](/solution/0700-0799/0705.Design%20HashSet/README_EN.md)
+- [Design HashMap](/solution/0700-0799/0706.Design%20HashMap/README_EN.md)
+
+### Database
 
 - [Combine Two Tables](/solution/0100-0199/0175.Combine%20Two%20Tables/README_EN.md)
 - [Second Highest Salary](/solution/0100-0199/0176.Second%20Highest%20Salary/README_EN.md)
@@ -193,8 +199,6 @@ You can also contribute to [doocs/leetcode](https://github.com/doocs/leetcode) u
 
 This project exists thanks to all the people who contribute.
 
-<!-- https://opencollective.com/doocs-leetcode/contributors.svg?width=890&button=false -->
-
 <a href="https://github.com/doocs/leetcode/graphs/contributors" target="_blank"><img src="./images/contributors.svg" /></a>
 
 ## Backers & Sponsors