expose rule metrics fields
expose rule metrics fields

Signed-off-by: Owen Diehl <b7f53a77a4950cb4aa47d9da3f442809e803fde5@gmail.com>

keegancsmith/prometheus,keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,keegancsmith/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,keegancsmith/prometheus,alileza/prometheus,alileza/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,keegancsmith/prometheus,alileza/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus