Publishing data access/api guidance

[odscrachel]

We could improve the documentation to make it clearer that we expect portals to have a public link to access JSON data and include some basic quality criteria. We should also consider adding some guidance regarding APIs.

[duncandewhurst]

We recently developed new API guidance for OCDS so the task is to adapt that for OC4IDS and add it to the docs.

We've already shared a subset of the guidance with implementers for feedback but haven't heard back from them so I suggest we proceed with adapting and adding the full guidance and then we can integrate the learnings from any feedback when we receive it.