adjust prompt to account for stacks, remove time from stack output

[ManoftheSea]

Description

Closes (already closed and stale) issue #3106

[robertcheramy]

Please describe your changes in CHANGELOG.md It would also be nice to provide some example prompts in /spec/model/data/fastiron#generic#prompt.yaml. See https://github.com/ytti/oxidized/blob/master/docs/ModelUnitTests.md#device-prompt