Fix README.md build command for DAWN-2018-02-14 branch
Fix README.md build command for DAWN-2018-02-14 branch

Signed-off-by: Joel <8af56de68279cb6f5ed022f31af18b9fcdcc2e92@example.com>

EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos