Make usage info more clear

src/main.rs

@@ -25,7 +25,7 @@ fn info(exe_name: &str) -> String {
         "nullbytes.\n",
         "If the second inputfile is larger, only ",
         "the size of the first inputfile is\n",
-        "processed and the rest will be ignored."
+        "processed and the rest of the second file will be ignored."
     ), VERSION, exe_name)
 }