Openset is a repository whose goal is to create a dataset created by people who use it. So for example, if I need some random text in french, I create a category named random-french-text, fork the repository, do the needed changes and finally open a pull request. One time this was done, one of the members of openset, verify the information as they can and if the information looks ok, they merge them.
It's an opportunity to add veritable test data, for your tech or things like that... I'm a developer too, but when I have to create just a template of my website about planes I don't know what to say about those planes. So, in this case, I can try to go on Openset and look if there is someone who did it and if YES I copy just the link of the raw JSON/YAML file, fetch it or download and use it. In the case it doesn't exists, you can do some research and contribute to the project.
If you want to join the Openset, open an issue and fill in all the needed data. In the case you're accepted you will have access to merge a pull request. In case of merging non-veritable data, or deleting data, the member is excluded from the project and joins the black-list. For each non-veritable data merged, a warn is added. At 3 warns the member is excluded.