correct typo

utils/nfc-mfclassic.c

@@ -582,7 +582,7 @@ print_usage(const char *pcProgramName)
  printf(" *** unlocked read does not require authentication and will reveal A and B keys\n");
  printf(" *** note that unlocked write will attempt to overwrite block 0 including UID\n");
  printf(" *** unlocking only works with special Mifare 1K cards (Chinese clones)\n");
- printf(" *** unlocking (w) also works for rewriting block 0 in gen2 clones\n");
+ printf(" *** unlocking (W) also works for rewriting block 0 in gen2 clones\n");
  printf(" a|A|b|B - Use A or B keys for action; Halt on errors (a|b) or tolerate errors (A|B)\n");
  printf(" u|U - Use any (u) uid or supply a uid specifically as U01ab23cd.\n");
  printf(" <dump.mfd> - MiFare Dump (MFD) used to write (card to MFD) or (MFD to card)\n");