Improve docker compatibility: Change the backup directory for ./nextcloud/data to reside within the host file system (basedir) so as to avoid moving the data folder back and forth between the docker container and the host file system. In situations where the nextcloud data takes up more than the free available space on the host system, this may lead to loosing some or all of the data.

Signed-off-by: MB-Finski <64466176+MB-Finski@users.noreply.github.com>

Improves docker compatibility. Placing the backup file in /var/www/ will cause a failure in rolling back the update on containerized setups ("Can only restore from ext/btrfs/zfs filesystems"). The host filesystem is most likely compatible so using $BASEDIR as the backup location *should* solve this issue for most users.

Signed-off-by: MB-Finski <64466176+MB-Finski@users.noreply.github.com>

Change backup directory for docker compatibility

Fixes a bening bug where the nextcloud update package won't be removed after unpacking when the code is run inside a docker container.

Also, for readability/clarity, remove an unnecessary "/var/www" from a cp command. 

Signed-off-by: MB-Finski <64466176+MB-Finski@users.noreply.github.com>