Minor fix in main.c file

main.c

@@ -22,7 +22,7 @@ struct parameters info = {
 Usage: ./inverT -i [<some.text.file>]\n\
   -help      Print help and exit.\n\
   -v         Print application version and exit.\n\
-  -i	     Invert text caracters.\n\
+  -i	     Invert text characters.\n\
 Example: ./inverT -i test.txt\n",
 };