+ fix -p in readme

Author: JafarAkhondali

README.md

@@ -29,8 +29,8 @@ xortool
 
 Usage:
   xortool [-x] [-m MAX-LEN] [-f] [-t CHARSET] [FILE]
-  xortool [-x] [-l LEN] [-c CHAR | -b | -o] [-f] [-t CHARSET] [-kp PLAIN] [FILE]
-  xortool [-x] [-m MAX-LEN| -l LEN] [-c CHAR | -b | -o] [-f] [-t CHARSET] [-kp PLAIN] [FILE]
+  xortool [-x] [-l LEN] [-c CHAR | -b | -o] [-f] [-t CHARSET] [-p PLAIN] [FILE]
+  xortool [-x] [-m MAX-LEN| -l LEN] [-c CHAR | -b | -o] [-f] [-t CHARSET] [-p PLAIN] [FILE]
   xortool [-h | --help]
   xortool --version