What marks a collection as documentation?

[oips]

We use Postman to publish collections. While trying to publish a new collection, we got the following error:

What makes it that one collections has documentation and another doesn’t?

I’m told that we have a limit of 25 published documentation, but we have way more than 25 published collections…

[oips]

Turns out all published collections are considered documentation. The confusion being that only things published since October 1st, 2022 are counted.