feat: update doc for new layouts symfony (#481)

Author: shakaran

Resources/doc/index.md

@@ -85,6 +85,13 @@ lexik_translation:
     base_layout: "LexikTranslationBundle::layout.html.twig"
 ```
 
+For new symfony or twig versions:
+
+```yml
+lexik_translation:
+    base_layout: "@LexikTranslation/layout.html.twig"
+```
+
 You can customize the edition grid by using input text or textarea fields.
 You can also shown/hidden similar columns on the grid. This means on the grid if a locale column is shown/hidden then similar locales columns will be shown/hidden too.
 (e.g.: if the col "en" is shown/hidden all "en_XX" cols will be shown/hidden too)