Add link to cleber's KVM Forum 2015 presentation
Add link to cleber's KVM Forum 2015 presentation

It's a great introductory presentation, and it will be
useful to new people interested in avocado.

Signed-off-by: Lucas Meneghel Rodrigues <8ad3460456640ab580599f5440c5a8d925a620b9@redhat.com>

apahim/avocado-framework.github.io