update plugin header for better search results

Author: ph

docs/index.asciidoc

@@ -14,7 +14,7 @@ END - GENERATED VARIABLES, DO NOT EDIT!
 
 [id="plugins-{type}-{plugin}"]
 
-=== Rubydebug
+=== Rubydebug codec plugin
 
 include::{include_path}/plugin_header.asciidoc[]