Remove the ADF images now that assets/ holds the game data

The build embeds assets/ and nothing reads the disk images any more.
desktop.ini only labelled the images in Windows Explorer, so it goes too.
skids extract --data <adfs> can still regenerate assets/ from a copy.

README.md

@@ -3,8 +3,9 @@
 A cross-platform (Windows, macOS, Linux) engine written in Rust that plays
 *Super Skidmarks* (Acid Software, 1995) on the original Amiga data.
 
-The game's data was converted from the original ADF disk images into
+The game's data was converted from the original ADF disk images (disks 2–6
-editable files in [`assets/`](assets/README.md):
+of the six-disk set) into editable files in [`assets/`](assets/README.md).
+The images themselves are no longer kept in this repository.
 
 - **Each track:** a 16-colour PNG (the PNG's palette is the track's
   palette), plus a text file with the lap gates and height map.

desktop.ini

@@ -1,6 +0,0 @@
-[LocalizedFileNames]
-Super Skidmarks (1995)(Acid Software)(AGA)(Disk 6 of 6)[HD].adf=@Super Skidmarks (1995)(Acid Software)(AGA)(Disk 6 of 6)[HD].adf,0
-Super Skidmarks (1995)(Acid Software)(AGA)(Disk 5 of 6)[HD].adf=@Super Skidmarks (1995)(Acid Software)(AGA)(Disk 5 of 6)[HD].adf,0
-Super Skidmarks (1995)(Acid Software)(AGA)(Disk 4 of 6)[HD].adf=@Super Skidmarks (1995)(Acid Software)(AGA)(Disk 4 of 6)[HD].adf,0
-Super Skidmarks (1995)(Acid Software)(AGA)(Disk 3 of 6)[HD].adf=@Super Skidmarks (1995)(Acid Software)(AGA)(Disk 3 of 6)[HD].adf,0
-Super Skidmarks (1995)(Acid Software)(AGA)(Disk 2 of 6)[HD].adf=@Super Skidmarks (1995)(Acid Software)(AGA)(Disk 2 of 6)[HD].adf,0