Update discussion of perturbation networks

[fjclark]

Proposed Change

Update the discussion of perturbation networks in the "Large-scale simulation planning" section, which was lifted from the V1 article.

Proposed Authors and Reviewers

Please volunteer (before the end of January) to author/ review and state when you're available. Authors, please say roughly when you plan to contribute the changes (no later than the end of May).

Proposed authors: @pitmanme @JenkeScheen?
Proposed reviewer: Volunteer wanted

[jmichel80]

I can review this section