highlight some sections in README

README.md

@@ -95,7 +95,7 @@ You can use it to:
 
 # Contribute code
 
-If you can fix any of the issues or add new features, you're welcome to send the PR to us. If the PR is accepted, your contribution will be scored from 0 to 5 points according to the difficulty and quality (higher is better). If you get 10 points, you can contact us for interviewing opportunities or recommendation letter for your future jobs.
+**If you can fix any of the issues or add new features, you're welcome to send the PR to us. If the PR is accepted, your contribution will be scored from 0 to 5 points according to the difficulty and quality (higher is better). If you get 10 points, you can contact us for interviewing opportunities or recommendation letter for your future jobs.**
 
 Make sure your code meets following requirements before submitting the PR:
 

README_cn.md

@@ -96,7 +96,7 @@
 
 # 贡献代码
 
-如果你可以修复某个issue或增加一个新功能, 欢迎给我们发送PR. 如果对应的PR被接受了, 你的贡献将会根据难度和质量在0-5区间内打分(越高越好). 如果你获得了10分, 你可以联系我们获得面试机会或为你未来的工作写推荐信。
+**如果你可以修复某个issue或增加一个新功能, 欢迎给我们发送PR. 如果对应的PR被接受了, 你的贡献将会根据难度和质量在0-5区间内打分(越高越好). 如果你获得了10分, 你可以联系我们获得面试机会或为你未来的工作写推荐信。**
 
 提交PR前请确认你的代码符合如下要求：