[Docs] Add note about multiple parameter in listbox (#4514)

* Add listbox note about multiple

* Wording

Author: vnbaaij

examples/Demo/Shared/Microsoft.FluentUI.AspNetCore.Components.xml

@@ -795,6 +795,11 @@
             </summary>
             <returns>The minimum value for the underlying type</returns>
         </member>
+        <member name="T:Microsoft.FluentUI.AspNetCore.Components.IStringParsableComponent">
+            <summary>
+            Defines an interface for components with values that can be parsed from a string.
+            </summary>
+        </member>
         <member name="P:Microsoft.FluentUI.AspNetCore.Components.IStringParsableComponent.ParsingErrorMessage">
             <summary>
             Gets or sets the error message to show when the field can not be parsed.

examples/Demo/Shared/Pages/List/Listbox/ListboxPage.razor

@@ -26,6 +26,16 @@
     </p>
 </blockquote>
 
+<blockquote>
+	<p>
+		<strong>Note:</strong> Although the component supports the <code>Multiple</code> parameter, the underlying web component does not correctly handle it.<br />
+		The selected items state will not correspond with the rendered options.<br />
+		<br />
+		We strongly advise <strong>not</strong> to use the <code>Multiple</code> parameter with the <code>&lt;FluentListbox&gt;</code> at this time.
+	</p>
+</blockquote>
+
+
 <h2 id="example">Examples</h2>
 
 <DemoSection Title="Manual" Component="@typeof(ListboxManual)"></DemoSection>