Fix doxygengroup documentation
Fix doxygengroup documentation

I failed to update it when changing away from :sections:.

AnthonyTruchet/breathe,kirbyfan64/breathe,RR2DO2/breathe,kirbyfan64/breathe,kirbyfan64/breathe,AnthonyTruchet/breathe,RR2DO2/breathe,AnthonyTruchet/breathe,kirbyfan64/breathe,AnthonyTruchet/breathe