set default_codec doc attribute

[skip ci] update gemspec summary

version bump for some docs fixes

Relax xmpp4r constraints

Relax constraints to be able to install the xmpp output with the xmpp
input.

Fixes #10

bump patch level for doc generation

Remove comment causing docgen issue

Fixes #9

dependency logstash-core-plugin-api >= 1.60 <= 2.99

Make sure all the gems were published under jruby

version 3.0.0

dependency logstash-core-plugin-api ~> 1.0