Add elements array to the example for SpdxPackage and SBOM

[goneall]

Per the discussion on the tech call, there was consensus that elements should have a minimum of 1 for both SpdxPackage and SBOM.

Fixes #1013

[goneall]

@JPEWdev - Please review

[NorioKobota]

If this is the correct specification, wouldn't it also be necessary to change External properties restrictions of Sbom class?
https://github.com/spdx/spdx-3-model/blob/main/model/Software/Classes/Sbom.md

## External properties restrictions

- /Core/ElementCollection/element
  - minCount: 1
- /Core/ElementCollection/rootElement
  - minCount: 1

Also, I think we need to discuss whether Bom and SpdxDocument classes should have at least one element, rootElement. In the end, the discussion will be whether element, rootElement in ElementCollection class should be minCount == 1.

[goneall]

If this is the correct specification, wouldn't it also be necessary to change External properties restrictions of Sbom class? https://github.com/spdx/spdx-3-model/blob/main/model/Software/Classes/Sbom.md

## External properties restrictions

- /Core/ElementCollection/element
  - minCount: 1
- /Core/ElementCollection/rootElement
  - minCount: 1

Thanks for providing the syntax for adding this - I created an issue in the model repo to add the restrictions, but I didn't have the information on how to modify the markdown files. See spdx/spdx-3-model#841

Also, I think we need to discuss whether Bom and SpdxDocument classes should have at least one element, rootElement. In the end, the discussion will be whether element, rootElement in ElementCollection class should be minCount == 1.

For ElementCollection we discussed on a tech call and agreed that an empty collection was acceptable, so having a minCount == 0 was OK. However, in a more recent tech call we reached a consensus that Bom and SpdxDocument (both subclasses of ElementCollection) should have a minimum of 1.

[zvr]

Please see my comment.
What do we decide for rootElement ?

This was triggered by SPDX Lite by @NorioKobota , which I am now updating to take into effect this new change.

[kestewart]

This aligns with decision in the model.