docs: Add strict trace continuation for React Native (#16984)

## DESCRIBE YOUR PR

Add `strictTraceContinuation` and `orgId` documentation to the React
Native distributed tracing guide.

**Changes:**
- **`react-native.mdx`** — Add strict trace continuation section with
explanation and code examples

## IS YOUR CHANGE URGENT?

- [ ] Urgent deadline (GA date, etc.):
- [ ] Other deadline:
- [x] None: Not urgent, can wait up to 1 week+

⚠️ Should be merged after
getsentry/sentry-react-native#5829 is released

## PRE-MERGE CHECKLIST

- [ ] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs (subject matter
experts)
- [ ] PR was reviewed and approved by a member of the [Sentry docs
team](https://github.com/orgs/getsentry/teams/docs)

Author: antonis

platform-includes/distributed-tracing/how-to-use/react-native.mdx

@@ -8,3 +8,33 @@ Sentry.init({
 ```
 
 If you're using version `5.9.x` or below, you'll need to have our <PlatformLink to="/tracing/">tracing feature enabled</PlatformLink> in order for distributed tracing to work.
+
+### Strict Trace Continuation
+
+When your application receives requests, they might include `sentry-trace` and `baggage` headers from an upstream service that is also using Sentry.
+By default, the SDK will continue the trace from these incoming headers. However, this behavior can be undesirable if the requests are from a third-party service,
+as it can lead to unwanted traces, increased billing, and skewed performance data.
+
+To prevent this, you can enable `strictTraceContinuation`. When this option is set to `true`, the SDK checks the incoming request for Sentry trace information and only continues the trace if it belongs to the same Sentry organization.
+Otherwise, it starts a new trace.
+
+```javascript {4}
+Sentry.init({
+  dsn: "___PUBLIC_DSN___",
+  tracesSampleRate: 1.0,
+  // Ensure that only traces from your own organization are continued
+  strictTraceContinuation: true,
+});
+```
+
+The SDK automatically parses the organization ID from your DSN. If you use a DSN format that doesn't include the organization ID (number followed by the letter `"o"`), or if you need to override it, you can provide it manually using the `orgId` option:
+
+```javascript {5}
+Sentry.init({
+  dsn: "___PUBLIC_DSN___",
+  tracesSampleRate: 1.0,
+  strictTraceContinuation: true,
+  // Manually provide your organization ID (overrides organization ID parsed from DSN)
+  orgId: 12345,
+});
+```