It is correct as it is now. It's your work alone that made the article is eligible for DYK, not Mattias321, so only you should be credited. If anyone makes significant improvements to the article before it hits the main-page, they can be credited aswell. The nomination-template also says "created/expanded by Struway2", so it's not a big deal. Recently, an article created by me, Edvard Skagestad, was featured in the DYK, but that was because of the work of , so only he got the credit from it.