Specification: Add example RO-Crates/snippets with new features described in version 1.2

[elichad]

Particular examples to target:

• example detached RO-Crate (requested by @simleo)
• snippets for the different ways one might reference an RO-Crate - particularly for this list which is very text-heavy

[elichad]

For detached crate, some existing crates to draw on:

From @stain
https://trefx.uk/5s-crate/0.4/#referencing-a-workflow-crate uses references to Workflow RO-Crate.
https://trefx.uk/5s-crate/0.4/example-request/data/ro-crate-preview.html - not detached but could be adapted
https://trefx.uk/5s-crate/0.4/example-request/data/ro-crate-preview.html#https%3A//workflowhub.eu/workflows/289%3Fversion%3D1 – but it is missing the conformsTo for RO-Crate as required now by 1.2 section.

From @ptsefton : https://data.ldaca.edu.au/api/object/arcp%3A%2F%2Fname%2Chdl10.4225~35~555d661071c76?meta=all detached but large