labs: add osbash/shutdown.sh symlink
labs: add osbash/shutdown.sh symlink

The recent changeset that added an "osbash shutdown.sh" line to
config/scripts.* was missing the symlink that makes the line work.

This patch adds the necessary symbolic link to the repo.

Change-Id: Ife4e1e2cbe2cca8c2eda34e5432c81db6284a24f

Nabs007/training-guides,Nabs007/training-guides,openstack/training-guides,Nabs007/training-guides,openstack/training-guides,harrisonfeng/training-guides,harrisonfeng/training-guides,harrisonfeng/training-guides