title: Custom create action in ActiveAdmin
body: <p>I am trying to add a custom create button in show page. I want only one create button in index page. I only want new button in show page alongside edit and delete.</p>
  
  <pre><code>ActiveAdmin.register User do
    permit_params :full_name, :email, :user_roles_id, :password, :password_confirmation
  
    action_item :create do
      link_to("New User", new_admin_user_path(@users), class: :button)
    end
  
    show do
      attributes_table do
        row :full_name
        row :email
        row :role do |user|
          auto_link user.user_role
        end
      end
    end
  end
  </code></pre>
  
  <p>I am getting two create buttons in index page for my model. It is also showing create new button in form as well. I want to remove create new button in form.</p>
  
  <p>Is there any inherit solution like showing all actions in <code>show</code> page for all models from <code>active_admin</code> config file?</p>