docs: Fix broken link

Author: deandreamatias

CONTRIBUTING.md

@@ -4,7 +4,7 @@ Thank you for considering and taking the time to contribute to this project!
 
 When contributing to this repository, please first discuss the change you wish to make via issue, email, or any other method with collaborators of this repository before making a change.
 
-Please note we have a [code of conduct](https://github.com/danvick/flutter_form_builder/CODE_OF_CONDUCT.md), please follow it in all your interactions with the project.
+Please note we have a [code of conduct](https://github.com/danvick/flutter_form_builder/blob/master/CODE_OF_CONDUCT.md), please follow it in all your interactions with the project.
 
 ## How to Contribute