If you look, there's a new tab that says "Decals". If you hover over it for description, it says "Vehicle Decals". Not sure what that is yet, but something was added.
I had to check this out by myself after reading your post. Indeed, you´re right it says "Vehicle Decals". I didn´t notice it yet.
So, I know decals from RC-Modelling and I seem to remember that on CoH2.org a community discussion had taken place in a thread (can´t remember which nor when) that debated the possibilty of customizing markings at your vehicles.
If you remember the skin of the german vehicles for example, you know that some of them have the description "SDKFZ XXX" or "Deutschland" on each side. I even believe that on some units there is the image of an jumping deer/elk shown.
So I suppose that this new tab could give us
the possibility to customize our vehicles with special descriptions or symbols.
Damn, that would be awesome.