By the monky’s tail, this has gone far too long!
I would suggest to change it in this forum for the glory of Rya.
@Tuxu, unfortunately, spell check is done by your browser (Google Chrome, Internet Explorer, Mozilla Firefox, etc.) not by the forum software. As such, there’s nothing we can do on our end to solve this.
That being said, you should be able to “add” hearthling to your browser’s custom dictionary so it will not complain further. How you do this depends on the browser. If you cannot determine how to do so, let me know what browser you use and I’ll give you a hand.
Alright then, not all website allow me to spellcheck so I thought it was some local plugin integrated into your forum.
Sites can choose to disable spell check in text fields, Discourse (the software) does not - so you get the browser spell check!
More details can be found at the HTML spec site.