Add Function to Notes for organizing illustrations, etc.

Please allow us to classify our notes by their function. For example, a note might be a translation of a text, commentary on a text, illustration of a passage or on a topic, application of a passage, explanation of a passage, etc., etc. If we could classify notes by their function, this could more easily enable us to organize various kinds of content in Notes and even have some of it surface in guides and other places.