add ignoreRoutes for SentryNavigatorObserver in sentry-dart

docs/platforms/flutter/integrations/routing-instrumentation.mdx

@@ -109,8 +109,6 @@ There are two ways to set up TTID:
 
 The default setup is enabled automatically, but only provides an approximation of TTID. To set a more accurate TTID, manually wrap the desired widget with `SentryDisplayWidget`, as shown below:
 
-
-
 ```dart
 import 'package:sentry_flutter/sentry_flutter.dart';
 
@@ -261,6 +259,20 @@ SentryNavigatorObserver(
 )
 ```
 
+### Ignore Routes
+
+Set `ignoreRoutes` if you want routes to be ignored and not processed by the navigation observer.
+Empty by default.
+
+```dart
+import 'package:sentry_flutter/sentry_flutter.dart';
+
+/// Ignore matching routes
+SentryNavigatorObserver(
+  ignoreRoutes: ["/ignoreThisRoute", "/my/ignored/route"],
+)
+```
+
 ### Override Transaction Name
 
 Set `setRouteNameAsTransaction` to `true` to override the transaction name with the route name.