Update docs/content_management/rich_text/create_custom_richtext_block.md

Author: mnocon

docs/content_management/rich_text/create_custom_richtext_block.md

@@ -29,7 +29,7 @@ In line 28, `my_block` is the same name of the block that you defined in line 3
 Line 28 also implements the `PreRender` method.
 Lines 41-51 handle the conversion of content into an XML string:
 
-``` php hl_lines="28 41-51"
+``` php hl_lines="28 37-47"
 [[= include_code('code_samples/back_office/online_editor/src/event/subscriber/RichTextBlockSubscriber.php') =]]
 ```