(doc) fix broken link

CONTRIBUTING.md

@@ -31,9 +31,9 @@ Getting Started
 
 + Make sure you have a [JIRA account](https://issues.apache.org/jira/).
 + Make sure you have a [GitHub account](https://github.com/signup/free).
-+ If you're planning to implement a new feature, it makes sense to discuss your changes 
-  on the [dev list](https://maven.apache.org/mail-lists.html) first. 
-  This way you can make sure you're not wasting your time on something that isn't 
++ If you're planning to implement a new feature, it makes sense to discuss your changes
+  on the [dev list](https://maven.apache.org/mail-lists.html) first.
+  This way you can make sure you're not wasting your time on something that isn't
   considered to be in Apache Maven's scope.
 + Submit a ticket for your issue, assuming one does not already exist.
   + Clearly describe the issue, including steps to reproduce when it is a bug.
@@ -44,15 +44,15 @@ Making and Submitting Changes
 --------------
 
 We accept Pull Requests via GitHub. The [developer mailing list][dev-ml-list] is the
-main channel of communication for contributors.  
+main channel of communication for contributors.
 There are some guidelines which will make applying PRs easier for us:
 + Create a topic branch from where you want to base your work (this is usually the master branch).
   Push your changes to a topic branch in your fork of the repository.
 + Make commits of logical units.
 + Respect the original code style: by using the same [codestyle][code-style],
   patches should only highlight the actual difference, not being disturbed by any formatting issues:
   + Only use spaces for indentation.
-  + Create minimal diffs - disable on save actions like reformat source code or organize imports. 
+  + Create minimal diffs - disable on save actions like reformat source code or organize imports.
     If you feel the source code should be reformatted, create a separate PR for this change.
   + Check for unnecessary whitespace with `git diff --check` before committing.
 + Make sure your commit messages are in the proper format. Your commit message should contain the key of the JIRA issue.
@@ -85,7 +85,7 @@ Additional Resources
 + [Apache Maven Twitter Account](https://twitter.com/ASFMavenProject)
 + #Maven IRC channel on freenode.org
 
-[dev-ml-list]: https://maven.apache.org/mail-lists.html
+[dev-ml-list]: https://maven.apache.org/mailing-lists.html
 [code-style]: https://maven.apache.org/developers/conventions/code.html
 [cla]: https://www.apache.org/licenses/#clas
 [maven-wiki]: https://cwiki.apache.org/confluence/display/MAVEN/Index