I would not want to clutter my ticklers or someday/maybes for something like that. I would put it in Reference.

I keep virtually no paper records, but I keep lots of digital records. I would label the software patch notification in an obvious way, and put it away.

If you trust yourself that you keep reference files, even if you forgot about it, if someone happens to ask for info on that software patch, you should first think "Maybe I did see something about it" and then "I bet it is in Reference."