Update license codelist and schema format

[odscrachel]

Related issues

Closes #123
Closes #281

Description

Outstanding questions @duncandewhurst

• is the description in the schema still okay as it is?
• will we update the examples now or do them at once, given a lot will change?

Merge checklist

If you added, removed or renamed a field:

• Update the collapse option of the jsonschema directives for dataset, resource, hazard, exposure, vulnerability and loss on reference/schema.md
• Update the diagrams in reference/schema/md
• Update the JSON files in examples

Always:

• Run ./manage.py pre-commit
• Update the changelog (style guide)

Having trouble?

See how to resolve check failures.

[duncandewhurst]

I've suggested updates to the description. We can leave updating the examples until all the schema and codelist changes are merged.

[duncandewhurst]

@odscrachel can we use this same PR to address #281? That way we can implement a shared definition for license and reuse it in both places.

[duncandewhurst]

The two outstanding suggestions from my previous review also need to be addressed.

[duncandewhurst]

@odscrachel I deleted the suggestion from my most recent review, because what we actually need to do is create a common License definition and reference it from both license and Source.license (rather than repeating the title, description, type etc. in both places).