getting permissions error with docker

Nobody has claimed this yet.

```
Matomo couldn't write to some directories (running as user 'www-data').

Try to Execute the following commands on your server, to allow Write access on these directories:

chown -R www-data:www-data /var/www/html
find /var/www/html/tmp -type f -exec chmod 644 {} \;
find /var/www/html/tmp -type d -exec chmod 755 {} \;
find /var/www/html/tmp/assets/ -type f -exec chmod 644 {} \;
find /var/www/html/tmp/assets/ -type d -exec chmod 755 {} \;
find /var/www/html/tmp/cache/ -type f -exec chmod 644 {} \;
find /var/www/html/tmp/cache/ -type d -exec chmod 755 {} \;
find /var/www/html/tmp/logs/ -type f -exec chmod 644 {} \;
find /var/www/html/tmp/logs/ -type d -exec chmod 755 {} \;
find /var/www/html/tmp/tcpdf/ -type f -exec chmod 644 {} \;
find /var/www/html/tmp/tcpdf/ -type d -exec chmod 755 {} \;
find /var/www/html/tmp/templates_c/ -type f -exec chmod 644 {} \;
find /var/www/html/tmp/templates_c/ -type d -exec chmod 755 {} \;
If this doesn't work, you can try to create the directories with your FTP software, and set the CHMOD to 0755 (or 0777 if 0755 is not enough). To do so with your FTP software, right click on the directories then click permissions.
```

DOcker should be running everything as root so I'm not sure why there are permission issues inside the container.

Start by reproducing the Matomo container permissions error and inspect ownership and access for /var/www/html and its tmp subdirectories while the process runs as www-data. Done means the container starts without the reported write-permission error and the listed directories remain usable by Matomo.

Written by the indexing model from the issue text.