callout for react router

Author: mydea

platform-includes/performance/configure-sample-rate/javascript.react.mdx

@@ -23,3 +23,8 @@ Sentry.init({
   tracePropagationTargets: ["localhost", /^https:\/\/yourserver\.io\/api/],
 });
 ```
+
+<Alert>
+  See [React Router](/platforms/javascript/guides/react/features/react-router/)
+  for more information on how to configure tracing with React Router.
+</Alert>