create and link reviewer checklist

[katjaq]

as part of the doc
could be provided as an md file checklist the reviewers could copy paste into they answers to the editor in the issue thread of the submission

[katjaq]

• linked to REVIEWERS.md file
• --> any editing will appear in the docs and in the website

[complexbrains]

I will be working on that since the previous one I had from Neuromatch, needs a bit modifying to do. So I assign this issue to myself as well if that is alright?

[lunebellec]

thanks @complexbrains ! Don't hesitate to tag me for review when you are done.