Revise note about Mirador and layer ordering for recipe 33

[triplingual]

Recipe info:

• Name: Multiple Choice of Images in a Single View (Canvas) Choice (simplest) #33
• link: https://iiif.io/api/cookbook/recipe/0033-choice/

Correction request

This is in anticipation of Mirador 4, which is not yet released. However, the previews (especially the layers test page) suggest that they've gone back to conformant layer ordering, starting with z-index 0 at the first painting annotation encountered. Though I haven't poked at it rigorously, if you go to the layers test page, use the Mirador "add resource" button and find the John Dee example, it uses the manifest from recipe 33. The x-ray version is the highest z-index as it should be. We should adjust the recipe text accordingly when it's out.

[triplingual]

(Status of "Needs Triage" not exactly accurate, but it's the closest thing to a waiting room.