doc: 更新测试工程

Author: ArgoZhang

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

@@ -8,5 +8,7 @@
 <DemoBlock Title="@Localizer["RegionNormalTitle"]"
            Introduction="@Localizer["RegionNormalIntro"]"
            Name="Normal">
-    <Region></Region>
+    <SelectRegion @bind-Value="Value"></SelectRegion>
+    <Display Value="@Value"></Display>
+    <Button OnClick="OnClick" Text="Update"></Button>
 </DemoBlock>

src/BootstrapBlazor.Server/Components/Samples/Regions.razor.cs

@@ -10,5 +10,10 @@ namespace BootstrapBlazor.Server.Components.Samples;
 /// </summary>
 public partial class Regions
 {
+    private string Value = "";
 
+    private void OnClick()
+    {
+        Value = "四川省-自贡市-大安区-团结镇";
+    }
 }