[Doc] Autoload Troubleshooting (#860)

* [Doc] Autoload Troubleshooting

* more detailed usage

* update to skip rector rule if children still not detected even with composer dump-autoload -o

build/target-repository/docs/static_reflection_and_autoload.md

@@ -52,3 +52,26 @@ Listed files will be executed like:
 ```php
 include $filePath;
 ```
+
+## Troubleshooting
+
+Sometime, when we run Rector to class that detect children class, like `\Rector\Privatization\Rector\Class_\FinalizeClassesWithoutChildrenRector`, we may experience that parent class changed to final while it has children class, it because of the `PHPStan\Reflection\ReflectionProvider` cannot get all classes on scanning it on usage via `FamilyRelationsAnalyzer` service.
+
+To avoid this issue, you may dump all classes via composer:
+
+```bash
+composer dump-autoload -o
+```
+
+before run the rector.
+
+If the false positive still happen, you can skip the rule applied as last resort to do:
+
+```php
+    $parameters->set(Option::SKIP, [
+        \Rector\Privatization\Rector\Class_\FinalizeClassesWithoutChildrenRector::class => [
+            // classes that has children, and not detected even with composer dump-autoload -o
+            __DIR__ . '/src/HasChildClass.php',
+        ],
+    ]);
+```