Update README.md

Author: mickhansen

README.md

@@ -36,7 +36,7 @@ To install 2.x.x branch - which has a unstable API and will break backwards comp
 - [Getting Started](http://sequelizejs.com/articles/getting-started)
 - [Documentation](http://sequelizejs.com/docs)
 - [API Reference](https://github.com/sequelize/sequelize/wiki/API-Reference) *Work in progress*
-- [Collaboration and pull requests](https://github.com/sequelize/sequelize/wiki/Collaboration)
+- [Collaboration and pull requests](https://github.com/sequelize/sequelize/blob/master/CONTRIBUTING.md)
 - [Roadmap](https://github.com/sequelize/sequelize/wiki/Roadmap)
 - [Meetups](https://github.com/sequelize/sequelize/wiki/Meetups)
 - [Twitter](http://twitter.com/sdepold)