include RTL CSS CDN URL in Download docs

_config.yml

@@ -30,4 +30,5 @@ expo:             http://expo.getbootstrap.com
 cdn:
   css:            //netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css
   css_theme:      //netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap-theme.min.css
+  css_rtl:        //netdna.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap-rtl.min.css
   js:             //netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js

docs/_includes/getting-started/download.html

@@ -33,6 +33,9 @@
 <!-- Latest compiled and minified CSS -->
 <link rel="stylesheet" href="{{ site.cdn.css }}">
 
+<!-- RTL (right-to-left) version of CSS -->
+<link rel="stylesheet" href="{{ site.cdn.css_rtl }}">
+
 <!-- Optional theme -->
 <link rel="stylesheet" href="{{ site.cdn.css_theme }}">