update readme to indicate that you must override the default download url
update readme to indicate that you must override the default download url

mrb/java,dcode/java,cposture/java,juliandunn/java,broadinstitute/java,GannettDigital/chef-java,mrb/java,cellux/java,udayas81/JAVA,gosquared/java,juliandunn/java,broadinstitute/java,cellux/java,LateRoomsGroup/java,cposture/java,cookbooks/hw-java,bitmonk/chef-java,foreflight/java,GannettDigital/chef-java,gsaslis/java,LateRoomsGroup/java,bitmonk/chef-java,RobertNorthard/java,cellux/java,mrb/java,foreflight/java,zenoss/java,gsaslis/java,bitmonk/chef-java,nshemonsky/chef-java,udayas81/JAVA,RobertNorthard/java,bgandon/java,foreflight/java,GannettDigital/chef-java,cookbooks/mc-java,dcode/java,cookbooks/oc-java,LateRoomsGroup/java,nshemonsky/chef-java,juliandunn/java,gsaslis/java,cposture/java,dcode/java,gosquared/java,nshemonsky/chef-java,bgandon/java,RobertNorthard/java,bgandon/java