[APM] Remove limitation about host metrics in otel docs

[colleenmcginnis]

Per @smith @AlexanderWert this limitation should be removed.

[github-actions]

A documentation preview will be available soon.

• 🔨 Buildkite builds
• 📚 HTML diff
• 📙 Preview page

Request a new doc build by commenting

• Rebuild this PR: run docs-build
• Rebuild this PR and all Elastic docs: run docs-build rebuild

_{run docs-build is much faster than run docs-build rebuild. A rebuild should only be needed in rare situations.}

_{If your PR continues to fail for an unknown reason, the doc build pipeline may be broken. Elastic employees can check the pipeline status here.}

[smith]

Thank you!

Does the limitations page direct users to use our otel collector distro?

This is still a limitation if you're sending data collected by the hostmetrics receiver directly to APM server without them being sent through the elasticinframetrics processor in the otel collector.

[colleenmcginnis]

Does the limitations page direct users to use our otel collector distro?

No. Last I heard we were waiting to integrate information on the Elastic Distribution of OpenTelemetry Collector until it was out of preview. cc @mlunadia

[AlexanderWert]

This is still a limitation if you're sending data collected by the hostmetrics receiver directly to APM server without them being sent through the elasticinframetrics processor in the otel collector.

@smith Since 8.15, the APM Server is also executing parts of the elasticinframetrics processor. So, it works there, too.