Minor doc fix.
Minor doc fix.

--filterworkers instead of --filterworks.

opentable/logstash-kafka,Aloomaio/logstash-kafka,tinglinux/logstash-kafka,joekiller/logstash-kafka,tinglinux/logstash-kafka,joekiller/logstash-kafka,Aloomaio/logstash-kafka,opentable/logstash-kafka