It might be a good idea to change the summary of this story to include something like "discontinued" or "abandoned" in it so people won't be disappointed when they start reading it and get to your note. On the other hand, thank you for leaving a note to let us know there won't be any more updates. Too many authors just simply abandon their stories and leave absolutely no indication that they have been abandoned, and the only way you can tell is by the lack of updates.