Document and define WIT IDs that are referenced elsewhere

[ggoodman]

As a newcomer coming to the Component Model, I was struggling to understand what a ID meant in the context of a WIT file. To help myself and others following in my footsteps, I took a stab at writing down what I thought I understood.

I don't expect this to be correct but hope we can use it as the starting point to get a solid definition in the reference doc.

[ggoodman]

Hi @lukewagner thanks for taking a look. The perceived gap in the document was understanding how deduplication happens. My understanding was that the deduplication happened on an ID basis. In the WIT Worlds section, we start referencing 'IDs' but I couldn't find any clear reference of what these IDs point to and what their components are. I may simply not have read attentively enough. I thought it would be helpful to have a little glossary-like section explaining the concept before it started getting used.

[lukewagner]

Yes, that makes sense and again I appreciate the work to improve the docs. Perhaps you could update the PR to add the new information to one of the existing sections (and add links to those sections where you think they're missing)?

[lukewagner]

I think #339 improves the situation for WIT identifiers, so I'll close this PR, but feel free to reopen if there's further changes you'd like to make.