feat: add builder doc (tpl)

docs/utils/editors/builder.md

@@ -78,6 +78,17 @@ class YourPage extends Page
 }
 ```
 
+Create a template:
+
+```twig-inline title="templates/page/your_page/default.html.twig"
+{% extends 'base.html.twig' %}
+
+{% block page %}
+    {{ _page.myBlock.value|block_to_html }}
+{% endblock %}
+```
+
+
 ## Creating custom block
 
 The easy way is to run: `php bin/console make:builder-block`.