adding issues template
adding issues template

sightmachine/LightGBM,huanzhang12/lightgbm-gpu,wxchan/LightGBM,huanzhang12/LightGBM,microsoft/LightGBM,Allardvm/LightGBM,Laurae2/LightGBM,cbecker/LightGBM,Laurae2/LightGBM,olofer/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,olofer/LightGBM,henry0312/LightGBM,wxchan/LightGBM,huanzhang12/lightgbm-gpu,fstonezst/LightGBM,Laurae2/LightGBM,huanzhang12/lightgbm-gpu,fstonezst/LightGBM,henry0312/LightGBM,cbecker/LightGBM,sightmachine/LightGBM,henry0312/LightGBM,huanzhang12/LightGBM,cbecker/LightGBM,fstonezst/LightGBM,Allardvm/LightGBM,wxchan/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,cbecker/LightGBM,sightmachine/LightGBM,olofer/LightGBM,Allardvm/LightGBM,microsoft/LightGBM,olofer/LightGBM,Allardvm/LightGBM,sightmachine/LightGBM,huanzhang12/lightgbm-gpu,microsoft/LightGBM,microsoft/LightGBM,huanzhang12/LightGBM,huanzhang12/LightGBM,microsoft/LightGBM,huanzhang12/lightgbm-gpu,wxchan/LightGBM,huanzhang12/LightGBM,fstonezst/LightGBM,wxchan/LightGBM,fstonezst/LightGBM,olofer/LightGBM,Allardvm/LightGBM