Whats this mean? In it the Ps4 update notes

The patch added some internal stuff to prep the game for when the DLC comes out, like the "add-ons" option on the title screen. First DLC comes out on Tuesday.

Ah, i thought it was to do with mods or something. Thanks

It has to do with that too, just like other recent Beth games, its a menu for turning on and off mods and DLC.

I threw a .esp in the data files and couldn't get it to register. I think that stuff is turned off until mod support rolls out for real, assuming its going through the main menu and they aren't adding a viewer in the launcher like before.

Mod I had installed when 1.4 went beta shows there, but a subsequent update removed them.

Since PC mods worked before and after the update, I think add-on support means resources that the DLC itself requires in order to function and not just resources to enable community made content. Like, in the past they've added things like animations and map markers (which the community then dissected to determine some details about the DLC), but I don't know the specifics of this update.