Adding a "no" option for early registration

[gestchild]

Our Events, Exhibitions and CollectionVenues custom types in Prismic have several select fields with single options

We've noticed that this causes a problem with Prismic's new page builder. If you select the 'yes' value there is no way to then unselect it, which could obviously cause issues if the value needs to be changed.

Ideally, we would make these into checkboxes, but that involves content migration - which has its own issues at the moment.

The easiest solution (which doesn't prevent us converting these to a checkbox in future), is to add a 'no' option to the select boxes.

We would also need to update the transformers to check for the value of the field