chore: document Datadog log forwarding

src/langsmith/deploy-to-cloud.mdx

@@ -123,7 +123,7 @@ When [creating a new deployment](#create-new-deployment), a new revision is crea
 
 ## View build and server logs
 
-Build and server logs are available for each revision.
+Build and server logs are available for each revision. LangSmith Cloud also supports native Datadog forwarding for server logs and traces. To enable Datadog logs, configure the deployment with `DD_API_KEY`, `DD_LOGS_ENABLED=true`, and `DD_LOG_INJECTION=true`. For more information, see [`DD_API_KEY`](/langsmith/env-var-cloud#dd_api_key).
 
 <Tabs>
   <Tab title="LangSmith UI">

src/snippets/langsmith/env-vars/shared.mdx

@@ -48,7 +48,9 @@ Defaults to `*` (all origins).
 
 Specify `DD_API_KEY` (your [Datadog API Key](https://docs.datadoghq.com/account_management/api-app-keys/)) to automatically enable Datadog tracing for the deployment. Specify other [`DD_*` environment variables](https://ddtrace.readthedocs.io/en/stable/configuration.html) to configure the tracing instrumentation.
 
-If `DD_API_KEY` is specified, the application process is wrapped in the [`ddtrace-run` command](https://ddtrace.readthedocs.io/en/stable/installation_quickstart.html). Other `DD_*` environment variables (e.g. `DD_SITE`, `DD_ENV`, `DD_SERVICE`, `DD_TRACE_ENABLED`) are typically needed to properly configure the tracing instrumentation. See [`DD_*` environment variables](https://ddtrace.readthedocs.io/en/stable/configuration.html) for more details. You can enable `DD_TRACE_DEBUG=true` and set `DD_LOG_LEVEL=debug` to troubleshoot.
+If `DD_API_KEY` is specified, the application process is wrapped in the [`ddtrace-run` command](https://ddtrace.readthedocs.io/en/stable/installation_quickstart.html). Other `DD_*` environment variables, such as `DD_SITE`, `DD_ENV`, `DD_SERVICE`, and `DD_TRACE_ENABLED`, are typically needed to properly configure the tracing instrumentation. See [`DD_*` environment variables](https://ddtrace.readthedocs.io/en/stable/configuration.html) for more details.
+
+To send logs to Datadog, also set `DD_LOGS_ENABLED=true`. Set `DD_LOG_INJECTION=true` to include trace and span identifiers in logs for trace correlation. You can enable `DD_TRACE_DEBUG=true` and set `DD_LOG_LEVEL=debug` to troubleshoot.
 
 <Note>
 Enabling `DD_API_KEY` (and thus `ddtrace-run`) can override or interfere with other auto-instrumentation solutions (such as OpenTelemetry) that you may have instrumented into your application code.