Update README for scrape-interval and export-interval flags.
Update README for scrape-interval and export-interval flags.

kawych/k8s-stackdriver,kawych/k8s-stackdriver,kawych/k8s-stackdriver,GoogleCloudPlatform/k8s-stackdriver,GoogleCloudPlatform/k8s-stackdriver,GoogleCloudPlatform/k8s-stackdriver,kawych/k8s-stackdriver