fix changelog example

CHANGELOG.md

@@ -6,13 +6,13 @@
 
 - Make response body accessible via hint in `beforSend` callback for failed web requests or if tracing is enabled in `SentryHttpClient` ([#2293](https://github.com/getsentry/sentry-dart/pull/2293))
   ```dart
-  options.beforeSend = (event, hint) async {
-    final response = hint.get(TypeCheckHint.httpResponse);
-    if (response is StreamedResponse) {
-      final body = await response.stream.bytesToString();
-      // user can now use it
-    }
-    return event;
+  options.beforeSendTransaction = (transaction, hint) {
+    final firstHint = transaction!.spans[0].hint;
+    final firstResponseBody = firstHint.get(TypeCheckHint.httpResponse);
+    final secondHint = transaction!.spans[1].hint;
+    final secondResponseBody = secondHint.get(TypeCheckHint.httpResponse);
+    // user can now use it
+    return transaction;    
   };
   ```
 - Support for screenshot PII content masking ([#2361](https://github.com/getsentry/sentry-dart/pull/2361))