add files for demo

caddy/Caddyfile

caddy/caddy.docker-compose.yml

docker-compose.yml

grafana/grafana.docker-compose.yml

nginx-exporter/nginx-exporter.docker-compose.yml

nginx/Dockerfile

nginx/index.html

nginx/nginx.conf

nginx/nginx.docker-compose.yml

postgres/postgres.docker-compose.yml

postgresql-exporter/postgresql-exporter.docker-compose.yml

prometheus/prometheus.docker-compose.yml

prometheus/prometheus.yml

todolist/.env

todolist/Dockerfile

todolist/todolist.docker-compose.yml

todolist/todolist.jar