Update Code Contribution link in README.md

README.md

@@ -97,7 +97,7 @@ Joining the Mattermost community is a great way to build relationships with othe
 #### Contribute
 
 - Share [feature ideas](http://www.mattermost.org/feature-requests/) with the Mattermost community
-- Review the [Mattermost Code Contribution Guidelines](https://github.com/mattermost/platform/blob/master/doc/developer/Code-Contribution-Guidelines.md) to submit patches for the core product
+- Review the [Mattermost Code Contribution Guidelines](https://github.com/mattermost/platform/blob/master/CONTRIBUTING.md) to submit patches for the core product
 - Build [community applications](http://www.mattermost.org/community-applications/) using Mattermost [webhooks, drivers and APIs](https://github.com/mattermost/platform/blob/master/doc/developer/API.md)
 - Create new [community installers and guides](http://www.mattermost.org/installation/#community-install-guide) for Mattermost