Update README.md

add the link to translate.wordpress.org

Author: patriciabt

README.md

@@ -75,7 +75,7 @@ Thanks to all translators for their great work.
 *  Norwegian (nb_NO) - Ibrahim Qraiqe
 *  Bulgarian (bg_BG) - [Vencislav Raev](http://www.catblue.net/)
 
-If you have created your own language pack, or have an update of an 
+You can translate this plugin on [translate.wordpress.org](https://translate.wordpress.org/projects/wp-plugins/multisite-language-switcher/), or if you prefer and have created your own language pack, or have an update of an 
 existing one, you can [send me](mailto:re@lloc.de) your gettext PO 
 and MO so that I can bundle it into the Multisite Language Switcher. 
 You can download the latest POT file