Added contributing section

Author: Tahanima

README.md

@@ -5,5 +5,8 @@ Welcome to the *LeetCode Solution Curation* repository! 👋
 
 *The contents of this repository will get published [here](https://tahanima.github.io/hello-leetcode/)*. So, don't forget to check it out.
 
+## Contributing
+Want to contribute? Please read our [CONTRIBUTING](.CONTRIBUTING.md) guidelines.
+
 ## License
 <a rel="license" href="https://opensource.org/licenses/MIT"><img alt="MIT License" style="border-width:0" height="50" src="https://w7.pngwing.com/pngs/514/841/png-transparent-mit-license-bsd-licence-open-source-license-copyright-miscellaneous-text-logo.png" /></a><br />This work is licensed under the <a rel="license" href="https://opensource.org/licenses/MIT">MIT License</a>.