Docs: Mapping set general & version IRIs

[joeflack4]

Overview

I was recently working with SSSOM, and I was trying to figure out which elements to use for:

1. Stable IRI: Stable IRI for the mapping set, which will yield the downloadable artefact of the latest version.
2. Version IRI: IRI for downloadable artefact of the particular version of the mapping set.

It seems that the element for (1) is mapping_set_id. However, I feel the documentation for it is ambiguous enough such that I can't discern if it means (1) or (2):

mapping_set_id: A globally unique identifier for the mapping set (not each individual mapping). Should be IRI, ideally resolvable.

As for (2), I can't find an element for it in the docs.