Installation Guide lacks whole disk user image creation guidelines.
To use agent drivers, we should use images created with the parameter
"vm", like: "disk-image-create ubuntu vm dhcp-all-interfaces -o my-image".
Change-Id: I82c30c20a1e1280beb8d30bfd3dd12df917172cb
Co-Authored-By: Lilia Sampaio <liliars@lsd.ufcg.edu.br>
Closes-Bug: #1514955