update README

README.md

 On server
 ==============
 
-* edit `/root/machine.conf` and update variables
-* configure only the internal IP addresses (applied to `eth0`).
-* create VM:
+* create default VM, attached to private network:
 ```shell
-virt-install-debian
+virt-install-debian srvXXX
 ```
-* add additional network interfaces, when needed
 
 Chef Bootstrapping (On Your Workstation)
 ========================================
@@ -23,3 +20,18 @@ Chef Bootstrapping (On Your Workstation)
     knife bootstrap --bootstrap-version 12.5.1 -E production -r "recipe[t3-base]" --ssh-gateway username@msXX.typo3.org \
       -N srvXXX.typo3.org 10.186.2.xx
 ```
+
+Customisation of virtual machine
+=====================================
+
+Feel free to customise the machine via /etc/libvir/qemu/*.xml files and tools.
+
+
+Update Config (On server)
+=====================================
+
+Optional, should not be required during daily operations
+
+* edit variables in `/root/machine.conf`
+
+Read the source of the shell script for further details