Add further clarification and align with wording in internal docs

[nicklas-dohrn]

Just a further improvement/alignment on this documentation to remove some ambiguity.

[JannikBrand]

To avoid duplication I would prefer to reference the span_passthrough parameter description from the configuration-parameter page.

Suggested change

	> When `span_passthrough` is set to `true`, spans are written to OpenSearch individually as they arrive, without assembling complete traces. This can be useful if you know that root/parent spans will be missing from your telemetry \(e.g., when only a subset of services in a request path emit spans\), so trace assembly cannot succeed anyway. In this case it lowers ingestion latency at the cost of trace completeness. Furthermore, when enabled, the `otel-v1-apm-service-map` index is not populated, so the Service Map view in the Observability plugin of OpenSearch Dashboards will not function and the Trace Analytics view may show orphaned spans rather than complete trace trees.
	> ### Note:
	> If you only need raw span data and do not require service map or full trace assembly, you can enable span passthrough mode (see [ingest_otlp configuration parameter](configuration-parameters-1830bca.md#loio1830bca1b060484e9cfabc0e62472e8e__table_zcy_jjx_jzb)):
	>
	> ```
	> {
	> "ingest_otlp": {
	> "enabled": true,
	> "span_passthrough": true
	> }
	> }
	> ```