* mark a few message for translation

* add translator documentation

classes/User.php

@@ -360,11 +360,12 @@ class User extends Memcached_DataObject
                                __FILE__);
                 } else {
                     $notice = Notice::saveNew($welcomeuser->id,
+                                              // TRANS: Notice given on user registration.
+                                              // TRANS: %1$s is the sitename, $2$s is the registering user's nickname.
                                               sprintf(_('Welcome to %1$s, @%2$s!'),
                                                       common_config('site', 'name'),
                                                       $user->nickname),
                                               'system');
-
                 }
             }
 
@@ -375,7 +376,6 @@ class User extends Memcached_DataObject
     }
 
     // Things we do when the email changes
-
     function emailChanged()
     {