Fixes #9331: betted PHP Callable Injection example

docs/guide/concept-di-container.md

@@ -95,29 +95,25 @@ $container->set('Foo', function () {
 $foo = $container->get('Foo');
 ```
 
-To hide the complex logic for building a new object, you may use a static class method to return the PHP
+To hide the complex logic for building a new object, you may use a static class method as callable. For example,
-callable. For example,
 
 ```php
 class FooBuilder
 {
     public static function build()
     {
-        return function () {
+        $foo = new Foo(new Bar);
-            $foo = new Foo(new Bar);
+        // ... other initializations ...
-            // ... other initializations ...
+        return $foo;
-            return $foo;
-       };        
     }
 }
 
-$container->set('Foo', FooBuilder::build());
+$container->set('Foo', ['app\helper\FooBuilder', 'build']);
 
 $foo = $container->get('Foo');
 ```
 
-As you can see, the PHP callable is returned by the `FooBuilder::build()` method. By doing so, the person
+By doing so, the person who wants to configure the `Foo` class no longer needs to be aware of how it is built.
-who wants to configure the `Foo` class no longer needs to be aware of how it is built.
 
 
 Registering Dependencies <span id="registering-dependencies"></span>