Hair ring(s) and their plurality

BUR #12705 has been rejected.

create alias hair_rings -> hair_ring

While a lot of characters have multiple hair rings, there are some that are typically portrayed with just a single one, like Alina Gray or Asari Nanami.
Another option would be to separate these into more tags, similar to hair buns - "hair_ring" as the catch-all, and then tags like single_hair_ring and double_hair_rings/twin_hair_rings (and multiple_hair_rings for 3+) emerging from it, implicating it.

I'm not sure about the utility of double hair rings, but you can make a single hair ring tag first and we'll see if it's enough that it impacts a search for the twin variant.

The bulk update request #12705 (forum #223681) has been rejected by @nonamethanks.