man: update knot conf

man/knot.conf.5.in

@@ -190,7 +190,7 @@ serves as an example of the configuration for knotc(8) and knotd(8).
  control {
 
   # Specifies interface, syntax is exactly the same as in 'interfaces' section
-  # Default: OFF
+  # Default: $(run_dir)/knot.sock
   listen-on "knot.sock";
 
   # As an alternative, you can use an IPv4/v6 address and port