Remove duplicated section (dotnet#16700)

Author: ernonewman

aspnetcore/mvc/views/tag-helpers/built-in/link-tag-helper.md

@@ -51,10 +51,6 @@ The CSS property name to use for the fallback test. For more information, see <x
 
 The CSS property value to use for the fallback test. For more information, see <xref:Microsoft.AspNetCore.Mvc.TagHelpers.LinkTagHelper.FallbackTestValue>.
 
-### asp-fallback-test-value
-
-The CSS property value to use for the fallback test. For more information, see <xref:Microsoft.AspNetCore.Mvc.TagHelpers.LinkTagHelper.FallbackTestValue>
-
 ## Additional resources
 
 * <xref:mvc/views/tag-helpers/intro>