Update cookbook-recipe.txt

For us, on line 126, without default: true being added, the user would not automatically be stored.

Author: benhatfield

content/docs/2_cookbook/7_extensions/0_permission-tricks/cookbook-recipe.txt

@@ -123,6 +123,7 @@ To make this work, the subpage blueprints needs to have a field that stores the
 author:
   type: users
   label: Author
+	default: true
   disabled: true
 ```