security/knock/pkg-descr: typo

Correct a slip of the finger in my previous commit.

security/knock/pkg-descr

@@ -4,6 +4,6 @@ interface for special "knock" sequences of port-hits.
 A client makes these port-hits by sending a TCP (or UDP) packet to a port on
 the server.  The port need not be open -- since knockd monitors at the
 link-layer level, it detects all traffic, even if destined for a closed port.
-When the server detects a specific sequence of c, it runs a command
+When the server detects a specific sequence of port-hits, it runs a command
 defined in its configuration file.  The command can be used to open holes in a
 firewall, for quick access.