While we are still in beta and until it starts populating, we are just going to have a single category "General" that all addons will go in. As the category starts filling up and as we get closer to release, we still start creating more specific categories and move them in accordingly.
Users, please note: These are addons that are for the beta of WoW Classic. They will not work on the Live servers!
Edit: We know folks are just trying to be helpful, but if an addon isn't yours, don't upload it!