[Serverless]: Security - Cases API links should point to serverless API reference

[joepeeples]

Serverless Docs

Elastic Security

Description

Affected pages:

• https://www.elastic.co/docs/current/serverless/security/cases-overview
• https://www.elastic.co/docs/current/serverless/security/cases-open-manage

These pages on cases include links to the Cases API, but the links go to the legacy stateful API docs. The links should probably go to the serverless API reference.

Not sure exactly which page/section they should target, maybe something like https://www.elastic.co/docs/api/doc/kibana/operation/operation-createcasedefaultspace?

Resources and additional context

n/a