Fix explanation

src/main/java/edu/kit/aifb/cii/pow/App.java

@@ -42,7 +42,7 @@ public class App {
         Options options = parseArguments(args);
         if (options == null) return;
 
-        // Try different targets. The maximum target is Integer.MAX (i.e., 2^32 -1)
+        // Try different targets. The maximum target is Integer.MAX (i.e., 2^31 -1)
         int target = (int) (Integer.MAX_VALUE * options.targetScaleFactor);
         Block genesis = makeGenesisBlock(target);