User stories and/or base use cases

Taken from @azaroth42's IIIF/api#1992, with some updates.

Requirement: Documentation enumerating base use cases and relevant user stories for use of 3D in IIIF.

Rationale: IIIF process is based around use cases. We need to know what we're trying to do, before trying to do it :)

Status: Some required use cases are listed at https://github.com/IIIF/iiif-3d-stories/issues. Additionally, the 3D Community Group has previously used a Google Form to collect user stories from the community. A summary of this process and results were described as part of the 3D Community Group update at the IIIF Fall Working Meeting 2020, and a log of the responses has been uploaded.

Next Steps:

Evaluate the use cases currently in the iiif-3d-stories GitHub to verify all should remain there, and then rephrase remaining use cases as user stories
User stories from the Google From log should be reviewed and appropriate stories should be contributed to the iiif-3d-stories GitHub
At some point the group should determine via community consensus when enough stories have been gathered to draw an "initial scope" for the 3D TSG work

IIIF / 3d

User stories and/or base use cases #2