[Doc] Documentation how to register custom SetList contant (#5921)

docs/how_to_register_custom_setlist_constant.md

@@ -0,0 +1,37 @@
+# How To Register Custom SetList Constant
+
+You can have custom `SetList` class that has constants that pointed to your own config, for example:
+
+
+```php
+<?php
+
+namespace App\Set\ValueObject;
+
+use Rector\Set\Contract\SetListInterface;
+
+class SetList implements SetListInterface
+{
+    public const MY_FRAMEWORK_20 = __DIR__ . '/../../../config/set/my-framework-20.php';
+}
+```
+
+Now, you can register your custom `SetList`'s constant via import from `$containerConfigurator`, for example:
+
+
+```php
+<?php
+// rector.php
+declare(strict_types=1);
+
+use Rector\Core\Configuration\Option;
+use App\Set\ValueObject\SetList;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+
+return static function (ContainerConfigurator $containerConfigurator): void {
+    $containerConfigurator->import(SetList::MY_FRAMEWORK_20);
+
+    $parameters = $containerConfigurator->parameters();
+    $parameters->set(Option::PATHS, [__DIR__ . '/src']);
+};
+```