adding note about cache

Author: Shinga13

README.md

@@ -1,6 +1,6 @@
 # SETS-Data
 The [release page](releases) contains compressed versions of the cargo data and images. **Ship
 images are not yet usable!** Download the archives and place them in your `.config` folder
-(replacing the existing `cargo` and `images` folder). This is a temporary solution until this cache
-is properly integrated into the SETS app.
- 
+(replacing the existing `cargo` and `images` folder). Make sure to delete your `cache` folder in
+order for the new cargo data to be available immediately. This is a temporary solution until this
+cache is properly integrated into the SETS app.