Missing logs under docker

:warning: If your issue is about an error during fetching a link, please read: http://doc.wallabag.org/en/user/errors_during_fetching.html#how-can-i-help-to-fix-that

### Issue details

I'm having an issue where I don't see any logs generated when running under docker.log I know they should be off of the wallaby install point var/log/prod.log (From https://doc.wallabag.org/en/user/errors_during_fetching.html#how-can-i-help-to-fix-that) however, I see app/AppKernel.php: return dirname(DIR) . '/var/logs'; (logs not log) and when I run inside docker I can generate errors and then do a find / -name prod.log and get no files.

### Environment

* Version: Docker image wallabag/wallabag:latest 29523e0152df
* Install via compose:
wallabag:
image: wallabag/wallabag
container_name: wallabag
restart: unless-stopped
environment:
- SYMFONY__ENV__DOMAIN_NAME=https://wallabag.TLD
volumes:
- wallabag_images:/var/www/wallabag/web/assets/images
- wallabag_data:/var/www/wallabag/data
- wallabag_logs:/var/www/wallabag/var/logs
* PHP/OS as included in docker
* Hosting: Personal docker type
* SQLite DB

### Steps to reproduce/test case

Try to log any error and find the log files.
NOTE running a redis import with env=prod *does* create log files as expected.