Fix Typo [mailinglist to mailing list]

CONTRIBUTING.md

@@ -24,7 +24,7 @@ Issues and merge requests should be in English and contain appropriate language
 
 Please help other GitLab users when you can.
 The channels people will reach out on can be found on the [getting help page](https://about.gitlab.com/getting-help/).
-Sign up for the mailinglist, answer GitLab questions on StackOverflow or respond in the IRC channel.
+Sign up for the mailing list, answer GitLab questions on StackOverflow or respond in the IRC channel.
 You can also sign up on [CodeTriage](http://www.codetriage.com/gitlabhq/gitlabhq) to help with one issue every day.
 
 ## I want to contribute!
@@ -191,4 +191,4 @@ This code of conduct applies both within project spaces and in public spaces whe
 
 Instances of abusive, harassing, or otherwise unacceptable behavior can be reported by emailing contact@gitlab.com
 
-This Code of Conduct is adapted from the [Contributor Covenant](http://contributor-covenant.org), version 1.1.0, available at [http://contributor-covenant.org/version/1/1/0/](http://contributor-covenant.org/version/1/1/0/)
+This Code of Conduct is adapted from the [Contributor Covenant](http://contributor-covenant.org), version 1.1.0, available at [http://contributor-covenant.org/version/1/1/0/](http://contributor-covenant.org/version/1/1/0/)
\ No newline at end of file