adds notes

src/Umbraco.Web/Mvc/UmbracoVirtualNodeRouteHandler.cs

@@ -15,6 +15,9 @@ namespace Umbraco.Web.Mvc
     {
         public IHttpHandler GetHttpHandler(RequestContext requestContext)
         {
+            //We are passing the singleton of UmbracoContext in here before assigning to a variable
+            //below because we are allowing a work around for FindContent to EnsureContext if necessary,
+            //this is a hack/work around for http://issues.umbraco.org/issue/U4-9384
             var found = FindContent(requestContext, UmbracoContext.Current);
             if (found == null) return new NotFoundHandler();