please add a license

[tomichec]

Thank you for publishing the culture guidelines.

Despite that you say it is open source, a proper license is missing in the repository. This could mean anything, even that you might still be able to claim exclusive copyright.

I wonder if you would mind to clarify it by adding a concrete license to the repository? (E.g. CC-BY-SA which ensures both the recognition to the authors but also ensures that the work remains free/libre.)

edit: better wording