NetScanner already has the ability to assign a comment to each address range. The yellow sticky note icon will let you set a comment and then display it when hovering over that button:
Another handy feature is outputting the bookmark name which the IP address belongs to in scan results. For that, you need to create a bookmark for each IP range, and tick "Show bookmark in output". Then you will be able to see which bookmark(s) each IP address belongs to: