ref(inventory): Make chroot target one child of target systems

This should allow just having a general 'target' system for ansible
which will take all the modifications - but not care whether we connect
to it locally (i.e. running from void) or through chroot.

We can set the connection method for the specific system(s) in whatever
we group as part of the target group then. For local installation we
simply add locally connected hosts and for chroot set up chrooted hosts.

play.yaml

@@ -4,7 +4,7 @@
 
 # Get python onto void - otherwise we can not interact through ansible
 - name: Bootstrap void python
-  hosts: chroot
+  hosts: target_system
   gather_facts: false
   tasks:
     - name: install python