Root preload URL

Author: maraf

src/Components/Endpoints/src/Builder/ResourcePreloadCollection.cs

@@ -57,6 +57,7 @@ private static (int order, string header) CreateHeader(StringBuilder headerBuild
     {
         headerBuilder.Clear();
         headerBuilder.Append('<');
+        headerBuilder.Append('/');
         headerBuilder.Append(url);
         headerBuilder.Append('>');