Clarify that <fieldset> only uses the disabled attribute

Fix #16632

docs/_includes/css/forms.html

@@ -256,7 +256,7 @@ <h3>Textarea</h3>
 
   <h3>Checkboxes and radios</h3>
   <p>Checkboxes are for selecting one or several options in a list, while radios are for selecting one option from many.</p>
-  <p>A checkbox or radio with the <code>disabled</code> attribute will be styled appropriately. To have the <code>&lt;label&gt;</code> for the checkbox or radio also display a "not-allowed" cursor when the user hovers over the label, add the <code>.disabled</code> class to your <code>.radio</code>, <code>.radio-inline</code>, <code>.checkbox</code>, <code>.checkbox-inline</code>, or <code>&lt;fieldset&gt;</code>.</p>
+  <p>Disabled checkboxes and radios are supported, but to provide a "not-allowed" cursor on hover, you'll need to add the <code>.disabled</code> class to the parent <code>.radio</code>, <code>.radio-inline</code>, <code>.checkbox</code>, or <code>.checkbox-inline</code>.</p>
   <h4>Default (stacked)</h4>
   <div class="bs-example" data-example-id="block-checkboxes-radios">
     <form>