Add context to Trace Observer restrictions

src/content/docs/distributed-tracing/concepts/how-new-relic-distributed-tracing-works.mdx

@@ -108,7 +108,7 @@ With Infinite Tracing, you can send us 100% of your trace data from your applica
       Only your spans go to the trace observer—all other data such as metrics, custom events, and transaction traces are sent the normal route to New Relic and are subject to local sampling.
     </Callout>
 
-    You configure a unique trace observer endpoint for the AWS region you want to send data to. You can request multiple endpoints, one per AWS region. The endpoint represents a trace observer for a particular workload. For example, all spans from a single trace (request) must go to that endpoint.
+    You configure a unique trace observer endpoint for the AWS region you want to send data to. Since Tracing is a cross-account feature, the trace observers are limited to one observer per region per [account family](https://docs.newrelic.com/docs/accounts/original-accounts-billing/original-users-roles/parent-child-account-structure/). You can request multiple endpoints, one per AWS region.  The endpoint represents a trace observer for a particular workload. For example, all spans from a single trace (request) must go to that endpoint.
 
     Here are two architectural diagrams: one showing how data flows if you use APM agents and another if you use New Relic integrations like OpenTelemetry exporters: