fixed broken links

CONTRIBUTING.md

@@ -25,8 +25,8 @@ This project loosely adheres to [Google Java Style][4] and is informed by
   * `com.google.common.base.Preconditions`
 
 [1]: https://code.usgs.gov/ghsc/nshmp/nshmp-lib/-/issues
-[2]: https://docs.gitlab.com/ee/gitlab-basics/fork-project.html
-[3]: https://docs.gitlab.com/ee/gitlab-basics/add-merge-request.html
+[2]: https://docs.gitlab.com/ee/user/project/repository/forking_workflow.html#creating-a-fork
+[3]: https://docs.gitlab.com/ee/user/project/merge_requests/creating_merge_requests.html
 [4]: https://google.github.io/styleguide/javaguide.html
 [5]: http://en.wikipedia.org/wiki/Joshua_Bloch#Effective_Java
 [6]: https://en.wikipedia.org/?title=UTF-8