Added metric docucmentation for ConsulDownMode
Added metric docucmentation for ConsulDownMode

Signed-off-by: Brandon Shroyer <d370be3f39cb88690ed16d1a7b77debc20949e86@pivotal.io>

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release