[make:twig-extension] Change folder for Twig Extension (#1211)

Co-authored-by: Oskar Stark <oskarstark@googlemail.com>

src/Maker/MakeTwigExtension.php

@@ -51,7 +51,7 @@ public function generate(InputInterface $input, ConsoleStyle $io, Generator $gen
     {
         $extensionClassNameDetails = $generator->createClassNameDetails(
             $input->getArgument('name'),
-            'Twig\\',
+            'Twig\\Extension\\',
             'Extension'
         );