Revert "doc: 移除多余箭头"

This reverts commit fce10f6.

Author: ArgoZhang

src/BootstrapBlazor.Server/Components/Pages/Install_Server.razor

@@ -64,7 +64,7 @@ var app = builder.Build();
 
         <Pre>// NET8/NET9
 &lt;BootstrapBlazorRoot&gt;
-    @@Body
+    &lt;@@Body
 &lt;/BootstrapBlazorRoot&gt;</Pre>
     </RootTemplate>
 </InstallContent>