doc: update deployment using s3 storage

examples/docker-compose.s3.yaml

@@ -21,6 +21,7 @@ services:
       - AWS_SECRET_KEY=xxxxx
       ## In case you are using S3 alternative such as Minio and your Minio instance is not secured, you change it to true
       - AWS_DISABLE_SSL="false"
+      - AWS_FORCE_PATH_STYLE=true # true for S3 alternative such as Minio
       # mysql-bkup container must be connected to the same network with your database
     networks:
       - web