Thank you for the immediate reply!The iwn(4) man page is often not updated to include every possible card combination either. As with most drivers it's not specific cards that are supported but a specific chip or chipset. The easiest way to test is to boot the install media, drop to a shell instead of install and look if your specific device is detected or not.
The iwn(4) driver has been included since FreeBSD 8 I think. Release notes often only mention new drivers or important changes to existing drivers.