Enhance Buildkite documentation with log correlation details

[gbrandrea]

This pull request updates the Buildkite CI Visibility documentation to include information about log collection and correlation. The main changes add details on how logs from Buildkite jobs can be collected, correlated, and managed within Datadog.

Enhancements to log collection and correlation:

• Added a new table entry describing "Logs correlation" and how to enable job log collection in the feature overview section.
• Added a dedicated "Collect job logs" section explaining how the integration collects logs, billing details, and how logs can be identified and managed in Datadog.
• Added a reference link to the Buildkite integration setup documentation to support the new log collection instructions.

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/andrea.prieguerodriguez/update_Buildkite_public_docs/continuous_integration/pipelines/buildkite