docs: enhance Caddy setup documentation and update Docker Compose configurations

- Add instructions for handling existing Docker networks in Caddy setup
- Update docker-compose.caddy.yml to specify external network name
- Modify docker-compose.example.yml to include network configuration for the default network

docker-compose.example.yml

@@ -37,4 +37,10 @@ services:
       timeout: 10s
       retries: 3
       start_period: 40s
+    networks:
+      - default
     # docker-entrypoint.sh handles migrations and server startup (with baseline fallback)
+
+networks:
+  default:
+    name: hoerdle_default