[Request]: Reference the ECS fields from the integrations doc pages

[alaudazzi]

Description

As a follow-up on https://github.com/elastic/observability-docs/issues/3968, we should reference the ECS fields definitions from each integrations doc page.

Resources

This document provide some background: https://docs.google.com/document/d/1I5GKUB8AWUdEhqNjhHE2CXDeUMHk3_kcMaI3xKbQ16g/edit

Which documentation set does this change impact?

Stateful and Serverless

Feature differences

None

What release is this request related to?

N/A

Collaboration model

The documentation team

Point of contact.

@zmoog @ishleenk17 @flash1293