Accessing config.yml variables in Bolt extensions -

i've set clean extension , trying pull in info extension's config.yml file. config.yml placed inside extension folder (at same level extension.php).

at moment i'm testing see if can retrieve config. here's whole extension.php:

<?php  namespace bolt\extension\andyjessop\vimeo;  use bolt\events\cronevent; use bolt\events\cronevents;  use bolt\application; use bolt\baseextension;  use symfony\component\httpfoundation\request; use symfony\component\httpfoundation\response;  class extension extends baseextension {      public function initialize() {          $this->app->get('api/update_video_content', array($this, 'updatevideocontent'))                   ->bind('updatevideocontent');      }      public function getname()     {         return "vimeo";     }      public function updatevideocontent()     {         $config = $this->config['user_id'];         $response = $this->app->json($config);         return $response;     } } 

and in config.yml:

access_token: xxxxxxxx user_id: xxxx api_base_url: https://api.vimeo.com/ 

but returns empty object. doing wrong here?

is config called config.yml.dist or config.yml.dist - note capital c, should lowercase? other that, after installation of extension config.yml.dist copied app/config/extensions/{extensionname}.config.yml , values in there used.