The Joystream Community Repo is a resource by the Joystream community with archived testnet content by founding members.
Although the community controls the repo, Jsgenesis has final say to approve and merge pull requests with code. The content is licensed under GPLv3. Community members with merge permission are @mochet and @traumschule.
The workflow for changing the repo depends on the reason and purpose behind the change. A consistent part is for the contributor to fork the repo, and create a pull request to the applicable branch. All changes need to be approved with a proposal. For details see the testnet workflow.