Hidden Entries Type to allow Modpack/Mod Devs to hide Entries in Chapters Tab to prevent clutter:
This would allow Modpack/Mod Devs to add a Hidden type to their Entries in a Chapter that would still be in the Entry Index but not in the Category Chapters, with this Modpack/Mod Devs would be able to still pull the Entry for things like clickable links within a non-hidden Chapter Entry but not in the Category Chapters part of the book which would reduce Chapter clutter if you have a lot of Chapters and only want to show off a few at all times.