doc: 更新示例

Author: ArgoZhang

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

@@ -5,10 +5,10 @@
 
 <h4>@Localizer["RegionDescription"]</h4>
 
+<PackageTips Name="BootstrapBlazor.Region" />
+
 <DemoBlock Title="@Localizer["RegionNormalTitle"]"
            Introduction="@Localizer["RegionNormalIntro"]"
            Name="Normal">
-    <SelectRegion @bind-Value="Value"></SelectRegion>
-    <Display Value="@Value"></Display>
-    <Button OnClick="OnClick" Text="Update"></Button>
+    <SelectRegion Value="@_value"></SelectRegion>
 </DemoBlock>

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

@@ -10,10 +10,5 @@ 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";
-    }
+    private string _value = "";
 }