Updates to Guidance Note Submission Checklist, and Reviewer Feedback Checklist

[Avnish95]

Guidance note is now in GitHub markdown, and aligned with the reproducibility verification guidelines, along with the submission checklist, and reviewer feedback checklist

[Avnish95]

Hi Maria, requesting your review on the updates to the Peer Code Review guidance note, package submission checklist, and the feedback checklist based on comments from Mer, Luise, Roshni, Ankriti, Mahin, as well as the general idea of aligning them with the reproducibility guidelines.

Thanks so much!

[mariaruth]

One more point that got cut off: i think it needs to be clearer in the guidance note that all reviewers fill out the checklist for overall code feedback (from which we'll remove reproducibility) and then fill out other checklists depending on the tasks requested for review.