Make our reviewer guidance accessible to the public

[dannylammerhirt]

Oru review process is complex, and often there are decisions to be made which dataset to pick, as well as how to assess it.

This process is not communicated in our frontend - neither on the entry page, nor in the methodology page (here we talk about the design of survey and datasets).

We have a reviewer guidance. We could open this guidance to the public and link it in our methodology page.

@tlacoyodefrijol - wann publish this document? https://docs.google.com/document/d/1drEj8cBVVxP7Ri-4SMIUsOdP6lLNcpQShpkx0rRdJLQ/edit