examples/readme/arg in cl-1.2.2 vs examples/readme/arg in cl-1.2.3

@@ -2,9 +2,11 @@
 $: << File.expand_path('lib')
 
 require 'cl'
 
 class Add < Cl::Cmd
+  register :add
+
   arg :owner
 
   def run
     p owner: owner
   end