Add FAQ section or tutorial: How to handle dynamic enum elements

[sdirix]

Use case: enum options are derived from other fields and queried from an API.

Example: https://jsonforms.discourse.group/t/dynamic-enum-values/837

Example: Country, Region, City

1. Define API and place in React context
2. Consume context in custom renderer
3. Trigger API to get country values -> Render them
4. In Region renderer: use useJsonForms() to resolve country data
5. Use country data against API to resolve regions
6. etc.

Optional: data resolving and fetch utils can be provided by a HOC