Doesn't have to be an actual field, can just be a guideline for how you should post titles. Speaking of guidelines, maybe that's worth adding as well? Something like Hackernews: https://news.ycombinator.com/newsguidelines.html - not advocating for these particular rules, just guidelines in general.
The year guideline would help when someone posts an older link, for example I think this submission: https://www.youtube.com/watch?v=YSUVRj8iznU with the title "Taproot, and Schnorr, and SIGHASH_NOINPUT, oh my!" would be better titled "Taproot, and Schnorr, and SIGHASH_NOINPUT, oh my! (2018)" since it's from 2018.