readme and docs: german and english game versions supported, what happens with other versions

docs/manual/20-troubleshooting.md

@@ -102,9 +102,12 @@ after an update, **Settings → Clear cache** throws it away; active mods are re
 
 ## FAQ
 
-**Do I need the German version of the game?**
-The tools were developed with the German CD. Other language versions use the same engine and
-should work; if one does not, please report it.
+**Which versions of the game work?**
+The German CD (`groove.exe` of 2001-02-12) and the English first release (2000-10-17) are
+supported, including every mod. With another version the level mods still work, but the mods
+marked *modifies groove.exe* stop with "unknown program version" – the first lines of
+`logs/apply.log` name the version LlamaMod found. Please report it together with that
+`groove.exe`, then it can be added.
 
 **Can I share levels with people who do not have the game?**
 No – levels are built from the receiver's own game copy. That is also what makes sharing legal: