[docs] Better description of this plugin needed

[suyograo]

https://www.elastic.co/guide/en/logstash/current/plugins-codecs-dots.html

[dwapstra]

Should at least state:

Codec that outputs a dot for every event

[v6]

// , I think the hilariously simple https://github.com/logstash-plugins/logstash-codec-dots/blob/master/lib/logstash/codecs/dots.rb kind of says it all, but I guess not everyone will think to look here.

@dwapstra does have a point.