fix: update NGINX configuration for improved backend service referencing and enhance docker-compose environment variable clarity

docker-compose.yml

@@ -5,7 +5,7 @@ services:
     container_name: adventurelog-frontend
     restart: unless-stopped
     environment:
-      - PUBLIC_SERVER_URL=http://server:8000 # MOST DOCKER USERS WILL NOT NEED TO CHANGE THIS EVER EVEN IF YOU CHANGE THE OUTWARD PORT
+      - PUBLIC_SERVER_URL=http://server:8000 # Should be the service name of the backend with port 8000, even if you change the port in the backend service
       - ORIGIN=http://localhost:8015
       - BODY_SIZE_LIMIT=Infinity
     ports: