Add README for SE-ResNeXt
Add README for SE-ResNeXt

lcy-seso/models,kuke/models,Superjom/models-1,lcy-seso/models,qingqing01/models,PaddlePaddle/models,PaddlePaddle/models,kuke/models,Superjom/models-1,lcy-seso/models,PaddlePaddle/models,qingqing01/models,kuke/models,qingqing01/models,Superjom/models-1,kuke/models