docs(ngDisabled): remove restriction to input element

Disabled can be set on many different elements, and might also be used
on custom controls, so it's better to remove the restriction completely

Closes #16775

src/ng/directive/attrs.js

@@ -181,7 +181,6 @@
       </file>
     </example>
  *
- * @element INPUT
  * @param {expression} ngDisabled If the {@link guide/expression expression} is truthy,
  *     then the `disabled` attribute will be set on the element
  */