Fix formatting for code samples

Fixes #771

Author: karenzone

docs/plugins/outputs/circonus.asciidoc

@@ -58,10 +58,16 @@ All values will be passed through `event.sprintf`
 
 Example:
 [source,ruby]
+-----
   ["title":"Logstash event", "description":"Logstash event for %{host}"]
+-----
+
 or
+
 [source,ruby]
+-----
   ["title":"Logstash event", "description":"Logstash event for %{host}", "parent_id", "1"]
+-----
 
 [id="plugins-{type}s-{plugin}-api_token"]
 ===== `api_token`