Add setup section to README
Add setup section to README

ershad/shipit-engine,perobertson/shipit-engine,Shopify/shipit-engine,perobertson/shipit-engine,Shopify/shipit-engine,perobertson/shipit-engine,ershad/shipit-engine,perobertson/shipit-engine,Shopify/shipit-engine,ershad/shipit-engine,perobertson/shipit-engine,Shopify/shipit-engine,ershad/shipit-engine,ershad/shipit-engine,Shopify/shipit-engine