Merge branch 'update-contribute-link' into 'master'

Redirect first Contribution link to about.gitlab.com/community/contribute

See merge request gitlab-org/gitlab-ce!28245

CONTRIBUTING.md

@@ -18,11 +18,11 @@ _This notice should stay as the first item in the CONTRIBUTING.md file._
 ## Contributing Documentation has been moved
 As of July 2018, all the documentation for contributing to the GitLab project has been moved to a new location.
-[View the new documentation](doc/development/contributing/index.md) to find the latest information.
+[View the new documentation](https://about.gitlab.com/community/contribute/) to find the latest information.
 ## Contribute to GitLab
-This [documentation](doc/development/contributing/index.md#contribute-to-gitlab) has been moved.
+[View the new documentation](https://about.gitlab.com/community/contribute/) to find the latest information.
 ## Security vulnerability disclosure
@@ -42,7 +42,7 @@ This [documentation](doc/development/contributing/index.md#helping-others) has b
 ## I want to contribute!
-This [documentation](doc/development/contributing/index.md#i-want-to-contribute) has been moved.
+[View the new documentation](https://about.gitlab.com/community/contribute/) to find the latest information.
 ## Contribution Flow