alias long nails -> long fingernails

BUR #15454 has been rejected.

create alias long_nails -> long_fingernails

Because I was trying to search for it earlier and couldn't find it

This bulk update request is pending automatic rejection in 5 days.

This bulk update request has been rejected because it was not approved within 45 days.

The bulk update request #15454 (forum #234672) has been rejected by @DanbooruBot.

It could also apply to long toenails, as written in the wiki.