Fix license link

Author: dgraham

Diff for: CONTRIBUTING.md

@@ -6,7 +6,7 @@
 
 Hi there! We're thrilled that you'd like to contribute to this project. Your help is essential for keeping it great.
 
-Contributions to this project are [released](https://help.github.com/articles/github-terms-of-service/#6-contributions-under-repository-license) to the public under the [project's open source license](LICENSE.md).
+Contributions to this project are [released](https://help.github.com/articles/github-terms-of-service/#6-contributions-under-repository-license) to the public under the [project's open source license](LICENSE).
 
 Please note that this project is released with a [Contributor Code of Conduct][code-of-conduct]. By participating in this project you agree to abide by its terms.