Fix contribution guidelines link in PR templates (apple#16)

Author: iSame7

.github/PULL_REQUEST_TEMPLATE.md

@@ -17,5 +17,5 @@ Replace this paragraph with a description of your changes and rationale. Provide
 ### Checklist
 - [ ] I've added at least one test that validates that my change is working, if appropriate
 - [ ] I've followed the code style of the rest of the project
-- [ ] I've read the [Contribution Guidelines](CONTRIBUTING.md)
+- [ ] I've read the [Contribution Guidelines](../CONTRIBUTING.md)
 - [ ] I've updated the documentation if necessary

.github/PULL_REQUEST_TEMPLATE/NEW.md

@@ -34,5 +34,5 @@ What is the impact of this change on existing users? Does it deprecate or remove
 ### Checklist
 - [ ] I've added at least one test that validates that my change is working, if appropriate
 - [ ] I've followed the code style of the rest of the project
-- [ ] I've read the [Contribution Guidelines](CONTRIBUTING.md)
+- [ ] I've read the [Contribution Guidelines](../../CONTRIBUTING.md)
 - [ ] I've updated the documentation if necessary