Fix sample snippet in the template guide
Fix sample snippet in the template guide

Fix a minor error in one of the sample snippets in the Instances
section of template guide. This will allow a user to copy and
paste and have the template work.

Change-Id: I35a59912fe6a4310c6000edfe2e969f5e8224664

miguelgrinberg/heat,pratikmallya/heat,openstack/heat,gonzolino/heat,cryptickp/heat,dims/heat,noironetworks/heat,maestro-hybrid-cloud/heat,cryptickp/heat,dragorosson/heat,maestro-hybrid-cloud/heat,jasondunsmore/heat,openstack/heat,takeshineshiro/heat,srznew/heat,takeshineshiro/heat,jasondunsmore/heat,srznew/heat,cwolferh/heat-scratch,noironetworks/heat,steveb/heat,miguelgrinberg/heat,dims/heat,dragorosson/heat,steveb/heat,cwolferh/heat-scratch,pratikmallya/heat,gonzolino/heat