Create a CODEOWNERS file so that it's easy to define who is able to approve Pull Requests

[chris-dco]

What

Create a CODEOWNERS file containing a list of all individuals and groups who are able to approve Pull Requests to the data-vocab repository.

Why

Unless you know it's not easy to determine who the approvers are for the data-vocab repository. By creating a CODEOWNERS file all individuals and groups who are able to approve Pull Request will automatically be added to the Pull Request and therefore improving developer experience.

[chris-dco]

Still required so that teams know who to contact in case of a PR.