Add contribution leaderboard to README

Added a contribution leaderboard image link to README.

Author: afc163

README.md

@@ -121,3 +121,7 @@ Any type of contribution is welcome, here are some examples of how you may contr
 - Use Ant Design Pro in your daily work.
 - Submit [issues](http://github.com/ant-design/ant-design-pro/issues) to report bugs or ask questions.
 - Propose [pull requests](http://github.com/ant-design/ant-design-pro/pulls) to improve our code.
+
+<a href="https://openomy.app/github/ant-design/ant-design-pro" target="_blank" style="display: block; width: 100%;" align="center">
+  <img src="https://openomy.app/svg?repo=ant-design/ant-design-pro&chart=bubble&latestMonth=3" target="_blank" alt="Contribution Leaderboard" style="display: block; width: 100%;" />
+</a>