README.adoc in relaton-cie-1.16.1 vs README.adoc in relaton-cie-1.16.2

@@ -27,26 +27,37 @@
 
     $ gem install relaton-cie
 
 == Usage
 
-=== Search document
+=== Configuration
 
+Configuration is optional. The available option is `logger` which is a `Logger` instance. By default, the logger is `Logger.new($stderr)` with `Logger::WARN` level. To change the logger level, use `RelatonCie.configure` block.
+
 [source,ruby]
 ----
 require 'relaton_cie'
 => true
 
+RelatonCie.configure do |config|
+  config.logger.level = Logger::DEBUG
+end
+----
+
+=== Search document
+
+[source,ruby]
+----
 item = RelatonCie::CieBibliography.get 'CIE 001-1980'
-[relaton-cie] ("CIE 001-1980") fetching...
-[relaton-cie] ("CIE 001-1980") found CIE 001-1980
+[relaton-cie] (CIE 001-1980) fetching...
+[relaton-cie] (CIE 001-1980) found `CIE 001-1980`
 => #<RelatonBib::BibliographicItem:0x007fb3f6098920
 ...
 
 # Return nil if a document doesn't exist.
 RelatonCie::CieBibliography.get '1111'
-[relaton-cie] ("1111") fetching...
-[relaton-cie] WARNING no match found online for 1111. The code must be exactly like it is on the standards website.
+[relaton-cie] (1111) fetching...
+[relaton-cie] WARNING no match found online for `1111`. The code must be exactly like it is on the standards website.
 => nil
 ----
 
 === Serialization