Fixes of docs in accordance with protocol of beanstalkd

lib/Beanstalk/Client.pm

@@ -961,17 +961,32 @@ The cumulative count of jobs created in this tube.
 
 =item *
 
+B<current_using> -
+The number of open connections that are currently using this tube.
+
+=item *
+
 B<current_waiting> -
 The number of open connections that have issued a
 reserve command while watching this tube but not yet received a response.
 
 =item *
 
+B<current_watching> -
+The number of open connections that are currently watching this tube.
+
+=item *
+
 B<pause> -
 The number of seconds the tube has been paused for.
 
 =item *
 
+B<cmd_delete> -
+The cumulative number of delete commands for this tube.
+
+=item *
+
 B<cmd_pause_tube> -
 The cumulative number of pause-tube commands for this tube.