Set default task fail threshold and add usage text

Signed-off-by: Sune Keller <[email protected]>
2 jobs for 15-docker-stack-waiter-is-too-brittle in 3 minutes and 35 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #399473783
docker
build

00:03:35

passed #399473784
docker
build-artifact

00:02:19