update image_reference metadata example to remove slug from image_path
update image_reference metadata example to remove slug from image_path

Signed-off-by: Mark Huang <222d07b3281cbd31b38f93d23c330586c713e995@pivotal.io>
Co-authored-by: Conor Nosal <03432e99a4c2912de17f57e1348738d567b5e293@pivotal.io>

pivotal-cf-experimental/pivnet-resource,pivotal-cf-experimental/pivnet-resource