Ensure folder `/var/lib/docker/volumes` exists

[markdumay]

Revise the function execute_install_bin() to ensure the folder /var/lib/docker/volumes exists. Below an excerpt of a related post on the Synology forum.

Create an empty volumes directory using sudo mkdir /var/lib/docker/volumes to make sure some poorly written code, like Portainer Agent, can find a valid directory there. It will not affect where volumes are saved (they will be correctly saved in /volume1/@docker