Adding words to the spell checker
I have started using Notebooks and I am finding that word I use frequently "tonnes" (the metric equivalent of a ton) is showing as mis-spelled. When I click on it, it pops up with the suggestion of "tones" which is not quite the same thing. How do I tell it to add "tonnes" to its dictionary. Or better still to stop being a luditte and get with the metric system.
I have set my dictionary to English, and my regional settings to New Zealand (we have been using the metric system here since I was a boy 40 years ago) but that does not seem to be the problem.