The HN guidelines[1] say:
> Don't solicit upvotes, comments, or submissions. Users should vote and comment when they run across something they personally find interesting—not for promotion.
I believe that means that asking people to leave positive comments on a post is something the guidelines ask you not to do.
But I would agree that, for instance, just posting on your social media "I posted this on HN, check out the comments" by itself should probably be fine, and might result in the same behavior, it's kind of a fuzzy line.
Please don't actually ask people to leave positive comments though. Or post something that you hope people read-between-the-lines the same way.