Add missing imports in migration example (#10291)

Author: AhmedAlaa4611

migrations.md

@@ -140,6 +140,9 @@ public function up(): void
 Sometimes a migration might be meant to support a feature that is not yet active and you do not want it to run yet. In this case you may define a `shouldRun` method on the migration. If the `shouldRun` method returns `false`, the migration will be skipped:
 
 ```php
+use App\Models\Flights;
+use Laravel\Pennant\Feature;
+
 /**
  * Determine if this migration should run.
  */