I feel like what you did might be considered spam - posting on FB groups, and reposting on HN. It's not adding any value to the community. But hey, what works, works.
If you post like that in a community of mine, I generally delete your post and blacklist your link preventing people from discussing it even if they discover it organically. There is just too much spam coming through to give benefit of the doubt.
If you want to announce something in someone else's community, I think fairer and more polite behaviour is to speak with an owner/moderator about what they think is fair - it might be that they allow such posts or they ask that you advertise, etc.