Updates README with wrk2 description, and detailed note about Coordinated Omission at the bottom
Updates README with wrk2 description, and detailed note about Coordinated Omission at the bottom

ahothan/wrk2,giltene/wrk2,khwangster/wrk2,Flipkart/wrk2,Flipkart/wrk2,jasonchaffee/wrk2,giltene/wrk2