Bump; TL;DR; Is there any documentation/tutorial on how to offer an *Update* action on top of the *Create* one ?
There’s not an explicit, top level, “update” action type, as you’ve seen - so “creates” are used for both create and update. Resources assume a single create method - so to add an update I’d look at either adding a discrete action for it, outside the resource; or break everything out of the resource and just do discrete operations. Resources are a convenience, but come with a little lack of control.
General tip: For your update operation be sure to think through the use case in terms of how the user will identify the object to be updated. For instance if you had a “Contact” resource, the user’s trigger likely will not know the contact_id from your system, but rather an email address or phone number, etc. You’ll want to add search actions to allow those lookups, or just take those alternate keys as the input.