CONTRIB: tcploop: report action 'K' (kill) in usage message

It was missing from the initial import.
diff --git a/contrib/tcploop/tcploop.c b/contrib/tcploop/tcploop.c
index 543e346..9e6d747 100644
--- a/contrib/tcploop/tcploop.c
+++ b/contrib/tcploop/tcploop.c
@@ -108,6 +108,7 @@
 	    "  A[<count>]   : Accepts <count> incoming sockets and closes count-1\n"
 	    "                 Note: fd=accept(fd)\n"
 	    "  J            : Jump back to oldest post-fork/post-accept action\n"
+	    "  K            : kill the connection and go on with next operation\n"
 	    "  G            : disable lingering\n"
 	    "  T            : set TCP_NODELAY\n"
 	    "  Q            : disable TCP Quick-ack\n"