Fix captureRouterTransitionStart for Next.js (#13347)

Author: smeubank

docs/platforms/javascript/guides/nextjs/manual-setup.mdx

@@ -94,35 +94,35 @@ Create three files in your application's root directory: `sentry.server.config.(
   slightly different, so copy them carefully.
 </Alert>
 
-```javascript {tabTitle:Client} {filename:instrumentation-client.(js|ts)} {"onboardingOptions": {"performance": "7-13", "session-replay": "5-6, 14-20"}}
+```javascript {tabTitle:Client} {filename:instrumentation-client.(js|ts)} {"onboardingOptions": {"performance": "5-10, 26-28", "session-replay": "11-19"}}
 import * as Sentry from "@sentry/nextjs";
 
-// This export will instrument router navigations. `captureRouterTransitionStart` is available from SDK version 9.12.0 onwards - upgrade if necessary!
-export const onRouterTransitionStart = Sentry.captureRouterTransitionStart;
-
 Sentry.init({
   dsn: "___PUBLIC_DSN___",
-  // Replay may only be enabled for the client-side
-  integrations: [Sentry.replayIntegration()],
-
   // Set tracesSampleRate to 1.0 to capture 100%
   // of transactions for tracing.
   // We recommend adjusting this value in production
   // Learn more at
   // https://docs.sentry.io/platforms/javascript/configuration/options/#traces-sample-rate
   tracesSampleRate: 1.0,
-
+  // Replay may only be enabled for the client-side
+  integrations: [Sentry.replayIntegration()],
+  
   // Capture Replay for 10% of all sessions,
   // plus for 100% of sessions with an error
   // Learn more at
   // https://docs.sentry.io/platforms/javascript/session-replay/configuration/#general-integration-configuration
   replaysSessionSampleRate: 0.1,
   replaysOnErrorSampleRate: 1.0,
-
+  
   // Note: if you want to override the automatic release value, do not set a
   // `release` value here - use the environment variable `SENTRY_RELEASE`, so
   // that it will also get attached to your source maps
 });
+
+// This export will instrument router navigations, and is only relevant if you enable tracing.
+// `captureRouterTransitionStart` is available from SDK version 9.12.0 onwards
+export const onRouterTransitionStart = Sentry.captureRouterTransitionStart;
 ```
 
 ```javascript {tabTitle:Server} {filename:sentry.server.config.(js|ts)} {"onboardingOptions": {"performance": "5-11"}}