doc: update README

Author: gengjiawen

README.md

@@ -1,5 +1,5 @@
-leetcode
-========
+# leetcode
+
 [![Gitpod ready-to-code](https://img.shields.io/badge/Gitpod-ready--to--code-blue?logo=gitpod)](https://gitpod.io/#https://github.com/gengjiawen/leetcode)
 [![CircleCI](https://circleci.com/gh/gengjiawen/leetcode.svg?style=svg)](https://circleci.com/gh/gengjiawen/leetcode)
 [![tested with jest](https://img.shields.io/badge/tested_with-jest-99424f.svg)](https://github.com/facebook/jest)
@@ -12,3 +12,5 @@ language.
 ![Leetcode](./leetcode.png?style=centerme)
 
 Just showoff I am a polyglot engineer.
+
+Also really try hard to mark TDD for every language :)