Fix links

Author: ajgarlag

docs/index.md

@@ -156,18 +156,14 @@ security:
 
 ## Contributing
 
-Please see [CONTRIBUTING](CONTRIBUTING.md) for details.
+Please see [CONTRIBUTING](/CONTRIBUTING.md) for details.
 
 ## Versioning
 
 This project adheres to [Semantic Versioning 2.0.0](https://semver.org/). Randomly breaking public APIs is not an option.
 
 However, starting with version 4, we only promise to follow SemVer on structural elements marked with the [@api tag](https://github.com/php-fig/fig-standards/blob/2668020622d9d9eaf11d403bc1d26664dfc3ef8e/proposed/phpdoc-tags.md#51-api).
 
-## Changes
-
-All the package releases are recorded in the [CHANGELOG](CHANGELOG.md) file.
-
 ## Reporting issues
 
 Use the [issue tracker](https://github.com/thephpleague/oauth2-server-bundle/issues) to report any issues you might have.