Added brief documentation to the ActiveAdmin initializer for the newly available options hash for CSS registration

Author: Matthew Brewer

lib/generators/active_admin/install/templates/active_admin.rb.erb

@@ -121,6 +121,9 @@ ActiveAdmin.setup do |config|
   # To load a stylesheet:
   #   config.register_stylesheet 'my_stylesheet.css'
   #
+  # You can provide an options hash for more control, which is passed along to stylesheet_link_tag():
+  #   config.register_stylesheet 'my_print_stylesheet.css', :media => :print
+  #
   # To load a javascript file:
   #   config.register_javascript 'my_javascript.js'
 end