added download instructions to README file. refs #3066
added download instructions to README file. refs #3066

ilios/ilios,stopfstedt/ilios,stopfstedt/ilios,thecoolestguy/ilios,justinchu17/ilios,justinchu17/ilios,justinchu17/ilios,ilios/ilios,thecoolestguy/ilios,Trott/ilios,justinchu17/ilios,dartajax/ilios,dartajax/ilios,Trott/ilios