For Drupal 7 we have this page:
What is the equivalent page where I can see the entries a field can have, for Drupal 8?
Where can I see that in
buildForm(array $form, FormStateInterface $form_state), to add an entry to $form, I should give an array with keys like "#type", "#title", "#required"? And how can I know the other possible keys?
Actually I'm using the Drupal 7 information in Drupal 8 and it works but there should/must be an updated page, I guess.