Fixed a missing cross reference

Author: javiereguiluz

form/create_custom_field_type.rst

@@ -90,8 +90,8 @@ shipping options.
 .. tip::
 
     If the purpose of this new form type was to customize the rendering of some
-    fields only, skip this step and use ``block_name`` or ``block_prefix`` option
-    instead. For more information, see :ref:`form-customization-form-themes`.
+    fields only, skip this step and use ``block_name`` or ``block_prefix`` options
+    instead to :ref:`define a custom form fragment name <form-fragment-custom-naming>`.
 
 .. tip::
 

form/form_themes.rst

@@ -275,6 +275,8 @@ form. You can also define this value explicitly with the ``block_name`` option::
 In this example, the fragment name will be ``_product_custom_name_widget``
 instead of the default ``_product_name_widget``.
 
+.. _form-fragment-custom-naming:
+
 Custom Fragment Naming for Individual Fields
 ............................................