docker compose exemplified, .env integration

DEPLOYMENT.md

@@ -115,6 +115,14 @@ CMD ["php", "-S", "0.0.0.0:8080", "-t", "public"]
 ```
 
 ### Docker Compose
+Use the example template as the base for a local override:
+
+```bash
+cp docker-compose.example.yml docker-compose.yml
+```
+
+Then adapt the local values as needed:
+
 ```yaml
 services:
   password-generator:
@@ -132,6 +140,7 @@ services:
       CORS_METHODS: "GET,POST,OPTIONS"
       CORS_HEADERS: "Content-Type,Authorization"
     volumes:
+      - ./.env:/var/www/html/.env:ro
       - ./logs:/var/www/html/logs
     restart: unless-stopped
 ```