Add NavigationSource

Author: reakaleek

src/Elastic.Markdown/IO/Navigation/DocumentationGroup.cs

@@ -198,8 +198,7 @@ protected DocumentationGroup(
 		GroupsInOrder = groups;
 		FilesInOrder = files;
 		NavigationItems = navigationItems;
-		Id = Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(FolderName + depth)))[..8];
-
+		Id = Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(NavigationSource + FolderName + depth)))[..8];
 		if (Index is not null)
 			FilesInOrder = [.. FilesInOrder.Except([Index])];
 	}