Minor improvement

Author: javiereguiluz

form/bootstrap4.rst

@@ -92,8 +92,8 @@ you'll get the error messages displayed *twice*.
 
     Since form errors are rendered *inside* the ``<label>``, you cannot use CSS
     ``:after`` to append an asterisk to the label, because it would be displayed
-    after the error message. Use the :ref:`label <reference-form-option-label-html>`
-    option instead.
+    after the error message. Use the :ref:`label <reference-form-option-label>`
+    or :ref:`label_html <reference-form-option-label-html>` options instead.
 
 Checkboxes and Radios
 ---------------------

reference/forms/types/form.rst

@@ -179,6 +179,8 @@ of the form type tree (i.e. it cannot be used as a form type on its own).
 
 .. include:: /reference/forms/types/options/label.rst.inc
 
+.. _reference-form-option-label-html:
+
 .. include:: /reference/forms/types/options/label_html.rst.inc
 
 .. include:: /reference/forms/types/options/row_attr.rst.inc