Mention checkboxes/radios options pre-setting in forms_api_reference.html

Just looked and reviewed the D7 form API reference examples. These additions are showing up.

Thanks for working to improve Drupal.

This is for the Drupal 7 Form API reference. Since Drupal 7 is past end-of-life this is now a "won't fix".

Work on documentation for form elements for supported versions of Drupal is at 📌 [meta] Move/Create Form Element Documentation Active and 🌱 [Meta] Improve documentation for Render and Form Elements Active .