There's no such category. Like "Tell HN" users made them up.
You should probably use "Show HN" https://news.ycombinator.com/showhn.html A good addition is to add a first comment like "author here, let me know if you have questions".
It exists, but it's not so formalized and reserved for YC
I tried a few google searches and nothing. Perhaps this would be better on StackOverflow or similar, but I like Ask HN and used it almost instinctively.