Update trace boundary documentation

Author: JoshuaMoelans

platform-includes/performance/add-spans-example/native.mdx

@@ -39,13 +39,15 @@ void perform_checkout() {
 This example will send a transaction named `checkout` to Sentry. The transaction will contain a `validation` span that measures how long `validate_shopping_cart()` took and a `process` span that measures `process_shopping_cart()`. Finally, the call to `sentry_transaction_finish()` will finish the transaction and send it to Sentry.
 
 ## Trace Boundaries
-By default, events, transactions, and spans will inherit the `trace_id` from the `propagation_context` as generated during SDK initialization. These values can be overridden by a downstream SDK that calls `sentry_set_trace(trace_id, parent_span_id)`, or by a user who can manually create a trace boundary using `sentry_generate_trace()`:
+By default, events will inherit the `trace_id` from the `propagation_context` as generated during SDK initialization. Finishing a transaction will generate a new trace, which will be stored on the `propagation_context` again for future events. Scoping a transaction with `sentry_set_transaction_object` will already use the new trace for events during the transaction lifetime.
+
+The `propagation_context` can be overridden by a downstream SDK that calls `sentry_set_trace(trace_id, parent_span_id)`, or by a user who can manually create a trace boundary using `sentry_regenerate_trace()`. Both will stop future transactions from creating new traces:
 
 ```c
 // Upon init, generates a random trace_id and span_id in the propagation_context
 sentry_options_t *options = sentry_options_new();
 sentry_init(options);
-// Events, transactions and spans will inherit the trace data from this propagation_context
+// Events will inherit the trace data from this propagation_context
 initialize_store();
 
 // trace_id and parent_span_id usually originate from a downstream SDK