readme: update the server requirement
readme: update the server requirement

h2o/h2o,yannick/h2o,cwyang/h2o,yannick/h2o,devnexen/h2o,cwyang/h2o,h2o/h2o,h2o/h2o,devnexen/h2o,devnexen/h2o,h2o/h2o,yannick/h2o,h2o/h2o,devnexen/h2o,devnexen/h2o,h2o/h2o,devnexen/h2o,yannick/h2o,h2o/h2o,cwyang/h2o,yannick/h2o,cwyang/h2o,yannick/h2o,cwyang/h2o,h2o/h2o,yannick/h2o,cwyang/h2o,yannick/h2o,h2o/h2o,cwyang/h2o,devnexen/h2o,devnexen/h2o,yannick/h2o,cwyang/h2o,devnexen/h2o