[Request]: Indicate in the tbs, central config, and custom roles docs that these features are not supported in serverless

[chrisdistasio]

Description

An extension of a recently completed ticket: #3394

There are a handful of features that are not available in Serverless--I would like to make a note in the stateful docs that these are not available in Serverless:

• Tail-based sampling: https://www.elastic.co/guide/en/observability/8.17/apm-sampling.html#apm-tail-based-sampling
• APM Agent central configuration: https://www.elastic.co/guide/en/observability/current/apm-agent-configuration.html
• Kibana Custom Roles: https://www.elastic.co/guide/en/observability/current/apm-feature-roles.html
  -- Note this is a single example of where I was able to locate some stateful o11y doc regarding custom roles. I'm not sure if there are other places as well that we should include this as there are no kibana custom roles available for any parts of o11y.

Resources

n/a

Which documentation set does this change impact?

Stateful only

Feature differences

not available in serverless.

What release is this request related to?

N/A

Collaboration model

The documentation team

Point of contact.

Main contact: @chrisdistasio

Stakeholders: @colleenmcginnis