doc: 更新文档示例

Author: ArgoZhang

src/BootstrapBlazor.Server/Components/Layout/MainLayout.razor

@@ -10,7 +10,7 @@
             <span class="sidebar-text">Bootstrap Blazor</span>
         </div>
         <NavMenu />
-        <LayoutSidebar Min="250" Max="380" ContainerSelector=".section"></LayoutSidebar>
+        <LayoutSplitebar Min="250" Max="380" ContainerSelector=".section"></LayoutSplitebar>
     </aside>
 
     <section class="main">