Updates docs with response_body

docs/index.asciidoc

@@ -25,7 +25,7 @@ Using this input you can receive single or multiline events over http(s).
 Applications can send an HTTP request to the endpoint started by this input and
 Logstash will convert it into an event for subsequent processing. Users 
 can pass plain text, JSON, or any formatted data and use a corresponding codec with this
-input. For Content-Type `application/json` the `json` codec is used, but for all other
+input. For content-type `application/json` the `json` codec is used, but for all other
 data formats, `plain` codec is used.
 
 This input can also be used to receive webhook requests to integrate with other services
@@ -101,6 +101,7 @@ This plugin supports the following configuration options plus the <<plugins-{typ
 | <<plugins-{type}s-{plugin}-max_pending_requests>> |<<number,number>>|No
 | <<plugins-{type}s-{plugin}-response_headers>> |<<hash,hash>>|No
 | <<plugins-{type}s-{plugin}-response_code>> |<<number,number>>, one of `[200, 201, 202, 204]`|No
+| <<plugins-{type}s-{plugin}-response_body>> |<<string,string>>|No
 | <<plugins-{type}s-{plugin}-ssl>> |<<boolean,boolean>>|No
 | <<plugins-{type}s-{plugin}-ssl_certificate>> |a valid filesystem path|No
 | <<plugins-{type}s-{plugin}-ssl_certificate_authorities>> |<<array,array>>|No
@@ -280,11 +281,22 @@ invalid credentials (401), internal errors (503) or backpressure (429).
 
 If 204 (No Content) is set, the response body will not be sent in the response.
 
+[id="plugins-{type}s-{plugin}-response_body"]
+===== `response_body`
+
+  * Value type is <<string,string>>
+  * Default value is `ok`
+
+The text body of the response returned to clients on successful POSTs.
+The default `ok` can be overriden with any string content such as JSON.
+
+If 204 (No Content) is set, the `response_body` option is ignored.
+
 [id="plugins-{type}s-{plugin}-response_headers"]
 ===== `response_headers` 
 
   * Value type is <<hash,hash>>
-  * Default value is `{"Content-Type"=>"text/plain"}`
+  * Default value is `{"content-type"=>"text/plain"}`
 
 specify a custom set of response headers
 

lib/logstash/inputs/http.rb

@@ -101,7 +101,7 @@ class LogStash::Inputs::Http < LogStash::Inputs::Base
   # Send reponses with this HTTP code. 204 is `no content`, and forces an empty response body
   config :response_code, :validate => [200, 201, 202, 204], :default => 200
 
-  # Send this as the body to each HTTP POST. A JSON example: `"{\"ok\": true}"`.
+  # Send this as the body to each HTTP POST. A JSON example: `'{"ok": true}'`.
   config :response_body, :default => "ok"
 
   # specify a custom set of response headers (use lowercase keys, per netty.io)