Update readme to incorporate using a GPU for training.
Update readme to incorporate using a GPU for training.


KangHsi/youtube-8m,KangHsi/youtube-8m,hxkk/u8m_test,forwchen/yt8m,lidalei/youtube-8m,slai11/youtube-8m,slai11/youtube-8m,mwoodson1/youtube-8m-competition,coded5282/youtube-8m,slai11/youtube-8m,google/youtube-8m,slai11/youtube-8m,forwchen/yt8m