[Serverless][Docs] Document the impact of using LogsDB for Serverless users

[gaurav-elastic]

Description
This epic aims to create documentation on the impact and benefits of using LogsDB in Elastic Serverless. The documentation will cover two primary scenarios:

1. users migrating from Elastic Cloud (ESS) to Serverless and
2. net new users adopting Serverless.
   The goal is to ensure users are well-informed about the changes and advantages associated with LogsDB in a serverless environment.

Tasks

1. Refer to [Request] [Draft] Document impact of using logsDB for security users #5864 where a lot of the work to document the changes has already been done.
2. Create a serverless specific doc to highlight the key changes, benefits, and user expectations.

Timeline
Ready for Serverless GA.