podman-compose startup issue

Solves issue #333. Error host not found in upstream "grafana:3000" due to startup of reverse-proxy service before grafana service. Adds grafana in the depends on section of the reverse-proxy. container.

• fixes spelling mistakes in rootless/README.md
• unifies nginx.conf into a single file
• adds depends on grafana for the reverse-proxy in all compose files

Let me know what you think & if you'd prefer to keep the definitions in the nginx.conf seperate.