Add vocabulary guide

[multimeric]

Designed to close #444.

[stain]

Thanks, @multimeric! Think we should include this, but just to improve navigation in case someone comes here before the spec, would you mind also adding links into https://www.researchobject.org/ro-crate/specification/1.2/profiles.html#extension-vocabularies and https://www.researchobject.org/ro-crate/specification/1.2/appendix/jsonld.html#adding-new-or-ad-hoc-vocabulary-terms at the first paragraphs? Considering this page will be found directly under "Resources" in menu.

I think also we can expand on how a profile should primarily try to use existing schema.org terms, for instance the Workflow Run Crate profile uses additional classes from the Action hierarchy. https://schema.org/docs/schemas.html can be used to find existing types.

[elichad]

haven't reviewed the text but adding to Stian's comment - you will also need to add the title and path to https://github.com/ResearchObject/ro-crate/blob/main/docs/_data/sidebars/resources.yml so it will show up in the Resources sidebar

[multimeric]

I've linked to the spec's section on extension vocabs. I'm not sure about the "Add local definitions of ad hoc terms" section considering my page is about importing vocabularies and not defining custom terms.

I think also we can expand on how a profile should primarily try to use existing schema.org terms, for instance the Workflow Run Crate profile uses additional classes from the Action hierarchy.

I also think this is out of scope because the audience of this article is people who need more precise, domain-specific vocabulary than schema.org. This is motivated by finding OBI which does a good job of describing our research metadata. I did mention schema.org in the first sentence though.