Document how to use Roles

[progval]

Is this the right place?

• This is NOT suggesting an addition, alteration or removal of CodeMeta terms. Please request terms changes in the main CodeMeta repository.
• This is NOT a request for the CodeMeta Generator. Please request Generator changes in the Codemeta-Generator repository.

What change or feature would you like to request?

Codemeta v3 added support for roles but it's not documented how to use them.

Here is a good example: oss-slu/Pi4Micronaut@fd6dc80 which does two optional things which I think are great:

1. having Person nodes directly as author values, and as value of the Role's author property (this makes it easier to parse for readers who don't care about nodes, including Codemeta v2 parsers)
2. uses id to deduplicate the nodes (which is easier to maintain, and somewhat forces parsers to handle JSON-LD correctly)

and we should strongly recommend doing that as well. (or maybe don't even mention it's possible to do otherwise)

Why is this needed.

Roles are tricky to use, not really documented on schema.org, and in Codemeta there is the extra complexity that the Role object needs its property to be compacted to schema:author instead of author.