changed README to reflect recent changes in build procedures
changed README to reflect recent changes in build procedures

cuihaoliang/zerovm,cuihaoliang/zerovm,zerovm/zerovm,zerovm/zerovm,zerovm/zerovm,cuihaoliang/zerovm,cuihaoliang/zerovm,zerovm/zerovm,zerovm/zerovm,cuihaoliang/zerovm