Fix class name.

manifests/setup.pp

@@ -77,7 +77,7 @@ class irc_bouncer::setup {
   }
 
 
-  class { '::letsencrypt::plugin::dns2136':
+  class { '::letsencrypt::plugin::dns_rfc2136':
     server              => 'ns-master.lysator.liu.se',
     keyname             => 'verdigris.lysator.liu.se',
     key_algorithm       => 'HMAC-SHA256',