title: How to use 'categorical slot' in form in rasa 3.x?
body: <p>I was trying to use 'categorical slot' in form in rasa 3.x but its not working as per the rasa 2.x 'categorical slot' . How to use 'categorical slot' in 'rasa 3.x' in correct way?
  I was using 'categorical slot' in rasa 3.x as below screenshot</p>
  <pre><code>main_menu:
      type: categorical
      values:
        - shop_with_us
        - call_us
      mappings:
      - type: from_text
        conditions:
        - active_loop: user_details_form
          requested_slot: main_menu
  </code></pre>