replace `docker` task with `buildDockerImage` task in README
replace `docker` task with `buildDockerImage` task in README

jrslv/elasticsearch,mwl/elasticsearch,mwl/elasticsearch,jhftrifork/elasticsearch,openwis-ss/elasticsearch,openwis-ss/elasticsearch,mwl/elasticsearch,frankscholten/elasticsearch,pekermert/elasticsearch,openwis-ss/elasticsearch,mesos/elasticsearch,frankscholten/elasticsearch,mwl/elasticsearch,pekermert/elasticsearch,mesos/elasticsearch,jhftrifork/elasticsearch,frankscholten/elasticsearch,jrslv/elasticsearch,jrslv/elasticsearch,jrslv/elasticsearch,openwis-ss/elasticsearch,jhftrifork/elasticsearch,mesos/elasticsearch,pekermert/elasticsearch,frankscholten/elasticsearch,mesos/elasticsearch,jhftrifork/elasticsearch,pekermert/elasticsearch