system-variables: add configuration tip based on units (#6664)

[ti-chi-bot]

This is an automated cherry-pick of #6664

What is changed, added or deleted? (Required)

This relates to #6622 -- since it gives advice based on units.

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TomShawn

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[TomShawn]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: cae60af