doc: 更新示例文档

Author: ArgoZhang

src/BootstrapBlazor.Server/Components/Samples/AutoCompletes.razor

@@ -8,7 +8,7 @@
 <DemoBlock Title="@Localizer["Block1Title"]" Introduction="@Localizer["Block1Intro"]" Name="Normal">
     <section ignore>@Localizer["NormalDescription"]</section>
     <div style="width: 200px;">
-        <AutoComplete Value="@_value" Items="@StaticItems" IsSelectAllTextOnFocus="true"></AutoComplete>
+        <AutoComplete Value="@_value" Items="@StaticItems" IsSelectAllTextOnFocus="true" IsClearable></AutoComplete>
     </div>
 </DemoBlock>