set default_codec doc attribute

Author: jsvd

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 5.2.1
+  - Docs: Set the default_codec doc attribute.
+
 ## 5.2.0
   - Added json_batch format
   - Make 429 responses log at debug, not error level. They are really just flow control

docs/index.asciidoc

@@ -1,5 +1,6 @@
 :plugin: http
 :type: output
+:default_codec: plain
 
 ///////////////////////////////////////////
 START - GENERATED VARIABLES, DO NOT EDIT!
@@ -382,3 +383,5 @@ See https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache
 
 [id="plugins-{type}s-{plugin}-common-options"]
 include::{include_path}/{type}.asciidoc[]
+
+:default_codec!:

logstash-output-http.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name            = 'logstash-output-http'
-  s.version         = '5.2.0'
+  s.version         = '5.2.1'
   s.licenses        = ['Apache License (2.0)']
   s.summary         = "Sends events to a generic HTTP or HTTPS endpoint"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"