adding USERS_GUIDE.html
adding USERS_GUIDE.html


Former-commit-id: f1c7052e800916b5ea3aa160a9d2390eb627dbca [formerly 94ce2d5ee3e468f1af88f865547841cdbb9a6761]
Former-commit-id: 8262fed551b473a113e1a8ebba851f8a085e391b
WEC-Sim/WEC-Sim