Fix typos is output doc
Fix typos is output doc

fixes #22
opentable/logstash-kafka,tinglinux/logstash-kafka,joekiller/logstash-kafka,opentable/logstash-kafka,tinglinux/logstash-kafka,joekiller/logstash-kafka,Aloomaio/logstash-kafka,Aloomaio/logstash-kafka