Fix doxygengroup documentation
Fix doxygengroup documentation

It seems I completely failed to proofread the copy and paste of examples
from the class docs to the group docs. Fixed up here. Fortunately
everything seems to work still.

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