doc: move bootstrap icon file

Author: ArgoZhang

src/BootstrapBlazor.Server/Components/App.razor

@@ -21,6 +21,7 @@
 
     <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor.FontAwesome/css/font-awesome.min.css"]" />
     <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor.MaterialDesign/css/md.min.css"]" />
+    <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor.BootstrapIcon/css/bootstrap.min.css"]" />
     <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor/css/bootstrap.blazor.bundle.min.css"]" />
     <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor/css/motronic.min.css"]" />
     <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor.Shared/BootstrapBlazor.Shared.bundle.scp.css"]" />

src/BootstrapBlazor.Shared/Components/Samples/Icons/BootstrapIcons.razor

@@ -2,10 +2,6 @@
 @layout MainLayout
 @inject IStringLocalizer<BootstrapIcons> Localizer
 
-<HeadContent>
-    <link rel="stylesheet" href="@Assets["_content/BootstrapBlazor.BootstrapIcon/css/bootstrap.min.css"]" />
-</HeadContent>
-
 <h3>@Localizer["Title"]</h3>
 
 <h4>@((MarkupString)Localizer["BaseUsageText"].Value)</h4>