[Issue]: Elasticsearch reference -> repositories.url.allowed_urls default value

[eedugon]

Type of issue

Missing information

What documentation page is affected

https://www.elastic.co/docs/reference/elasticsearch/configuration-reference/snapshot-restore-settings

What happened?

The setting repositories.url.allowed_urls that is mentioned in some data migration guides when the URL readonly repository is mentioned doesn't have a default value documented, neither it's mentioned that is a list.

I think we should clarify what's the default value, even if it's an empty list.

Additional info

No response