Update Contributing doc. [CI skip]

CONTRIBUTING.md

@@ -4,13 +4,19 @@ Thank you for your interest in contributing to this GitLab project! We welcome
 all contributions. By participating in this project, you agree to abide by the
 [code of conduct](#code-of-conduct).
-## Contributor license agreement
-By submitting code as an individual you agree to the [individual contributor
-license agreement][individual-agreement].
-By submitting code as an entity you agree to the [corporate contributor license
-agreement][corporate-agreement].
+## Developer Certificate of Origin + License
+By contributing to GitLab B.V., You accept and agree to the following terms and
+conditions for Your present and future Contributions submitted to GitLab B.V.
+Except for the license granted herein to GitLab B.V. and recipients of software
+distributed by GitLab B.V., You reserve all right, title, and interest in and to
+Your Contributions. All Contributions are subject to the following DCO + License
+terms.
+
+[DCO + License](https://gitlab.com/gitlab-org/dco/blob/master/README.md)
+
+_This notice should stay as the first item in the CONTRIBUTING.md file._
 ## General issue guidelines
@@ -161,5 +167,3 @@ This Code of Conduct is adapted from the [Contributor Covenant][contributor-cove
 available at [http://contributor-covenant.org/version/1/1/0/](http://contributor-covenant.org/version/1/1/0/).
 [contributor-covenant]: http://contributor-covenant.org
-[individual-agreement]: https://docs.gitlab.com/ee/legal/individual_contributor_license_agreement.html
-[corporate-agreement]: https://docs.gitlab.com/ee/legal/corporate_contributor_license_agreement.html