Everybody who was previously in the 'Donator' user-group was put into the 'Onyx' user-group for free.
'Donator' isn't an upgrade group anymore, so by default, you're now 'Onyx'. Congrats.
You're now an Onyx member, Donator was removed because Power+ is being implemented. Philly believed four upgrades is to many, so he deleted Donator entirely and upgraded all the Donators to Onyx. Congratulations and enjoy!