I just recently downloaded the Turnkey Tracks for VM, works great but was wondering how this gets updates, seems I'm a bit problematic/clumsy to keep on installing new images, so guessing I am missing somthing,. 

I have had a look through GitHub not found anything relevant to do with Turnkey / Debian installs, docker seems to be the fad now.
 

I'm a bit of a newbie to this, I have some basic Linux knowledge more in the area of security/hardening so a little out of my depth here, any help would be appreciated.