Updated i18n docs

docs/en/topics/i18n.md

@@ -67,14 +67,35 @@ Formats can be set globally in the i18n class. These settings are currently only
 to write your own logic for any frontend output.
 
 	:::php
-	i18n::set_date_format('dd.MM.YYYY');
-	i18n::set_time_format('HH:mm');
+	Config::inst()->update('i18n', 'date_format', 'dd.MM.YYYY');
+	Config::inst()->update('i18n', 'time_format', 'HH:mm');
 
 Most localization routines in SilverStripe use the [Zend_Date API](http://framework.zend.com/manual/en/zend.date.html).
 This means all formats are defined in
 [ISO date format](http://framework.zend.com/manual/en/zend.date.constants.html#zend.date.constants.selfdefinedformats),
 not PHP's built-in [date()](http://nz.php.net/manual/en/function.date.php).
 
+### Language Names
+
+SilverStripe comes with a built-in list of common languages, listed by locale and region.
+They can be accessed via the `i18n.common_languages` and `i18n.common_locales` [config setting](/topics/configuratio).
+
+In order to add a value, add the following to your `config.yml`:
+
+	:::yml
+	i18n:
+	  common_languages:
+	    de_CGN:
+	      name: German (Cologne)
+	      native: Kölsch
+
+Similarly, to change an existing existing language label, you can overwrite one of these keys:
+	
+	i18n:
+	  common_languages:
+	    en_NZ:
+	      native: Niu Zillund
+
 ### i18n in URLs
 
 By default, URLs for pages in SilverStripe (the `SiteTree->URLSegment` property)