Minor update, no writable layer by default

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

Author: troglobit

_posts/2024-03-08-containers.md

@@ -87,12 +87,17 @@ the Alpine Linux image.
 admin@infix:/> configure
 admin@infix:/config> edit container web
 admin@infix:/config/container/web/> set image docker://nginx:alpine
+admin@infix:/config/container/web/> set volume cache target /var/cache
 admin@infix:/config/container/web/> edit network
 admin@infix:/config/container/web/network/> set interface docker0
 admin@infix:/config/container/web/network/> set publish 8080:80
 admin@infix:/config/container/web/network/> leave
 ```
 
+> Infix does not create a writable layer by default, so you need to
+> explicitly add *volumes* for directories your container needs.
+{: .prompt-info }
+
 Issuing the command `leave` queues a job to download the image and
 create a container in the background.  To see the progress: