bundler is not needed anymore as a debian package

docs/source/development.rst

@@ -35,7 +35,7 @@ Also make sure you have ``Git`` installed. `Details <http://git-scm.com/book/en/
     Windows users should use Chocolatey as recommended above.:
 
 .. note::
-    Debian & Ubuntu users : apt-get install git npm nodejs-legacy bundler
+    Debian & Ubuntu users : apt-get install git npm nodejs-legacy
 
 Once you have *Node.js* and *git* installed, run the following command inside the Converse.js
 directory: