Applying DCO to all devfile repositories

[elsony]

Which area/kind this issue is related to?
/area api
/area library
/area registry
/area devworkspace
/area integration-tests
/area test-automation

NOTE: This also applies to the product registry.

Issue Description

Applying DCO to all devfile repositories:

• add a file to the root directory of your project repository containing just the text of version 1.1 of the DCO (example: https://github.com/metal3-io/metal3-docs/blob/master/DCO).

• add the following text to a CONTRIBUTING.md file in the root directory of your project repository:

  Certificate of Origin

  By contributing to this project you agree to the Developer Certificate of
  Origin (DCO). This document was created by the Linux Kernel community and is a
  simple statement that you, as a contributor, have the legal right to make the
  contribution. See the DCO file for details.

Background Info:
With the recent Github announcement about enabling DCO (Developer Certificate of Origin) sign offs, the architects team discussed enabling this new feature in all our github repos, so as to be consistent.

Please document DCO practice in your repo

DCO basically is a way for a contributor to express they can contribute to a project, according to the project's licensing requirements. It signifies that the contributor has the right to submit the contribution under the applicable open source license of the project.

[yangcao77]

docker-plugin left

[thepetk]

Closing in favor of #1618