readme: add build status icon
readme: add build status icon

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