On updated event.
document events all have 3 out-pins you can use:
Current Document will contain the document which is updated and will have the newest version of the document with the updated values.
Revisions is an array with objects that contains what updates were made to the document. A revision object will have the fields
key, which is the field that is updated.
type, what update was made, (set.field, remove.field, array.add, etc.).
value, has the new value for that field.
previous_value, has the old value.
Fields Modified is an array with values. Each item in this array will be a field that has been updated, either removed, updated or created.