doc: building bigdl core
doc: building bigdl core

qiuxin2012/BigDL,wzhongyuan/BigDL,i8run/BigDL-1,luchy0120/BigDL,zhangxiaoli73/BigDL,zhangxiaoli73/BigDL,zhangxiaoli73/BigDL,luchy0120/BigDL,wzhongyuan/BigDL,qiuxin2012/BigDL,jenniew/BigDL,i8run/BigDL-1,jenniew/BigDL,yiheng/BigDL,jenniew/BigDL,wzhongyuan/BigDL,qiuxin2012/BigDL,yiheng/BigDL,yiheng/BigDL,i8run/BigDL-1,luchy0120/BigDL