Document that the message is read from stdin.

src/lyskom/notify_lyskom.c

@@ -45,7 +45,8 @@ usage(void)
 {
     printf("%s: usage: %s [ options... ] recipients...\n",
 	   argv0, argv0);
-    printf("Each recipient is a decimal conference number.  Valid options:\n");
+    printf("Each recipient is a decimal conference number.  The message\n");
+    printf("is read from stdin.  Valid options:\n");
     printf("  --       Marks end of options.\n");
     printf("  -H<ip>   IP address of LysKOM server host.\n");
     printf("  -P<port> Port of LysKOM server.\n");