update README.md
update README.md

- add troubleshooting section for an issue I encountered while running hashi-ui behind and AWS ELB
- add a helpful (required?) docker argument
maytechnet/nomad-ui,Wintermute1/hashi-ui,iverberk/nomad-ui,maytechnet/nomad-ui,Wintermute1/hashi-ui,jippi/hashi-ui,maytechnet/nomad-ui,maytechnet/nomad-ui,iverberk/nomad-ui,jippi/hashi-ui,Wintermute1/hashi-ui,jippi/hashi-ui,Wintermute1/hashi-ui,iverberk/nomad-ui