Upon request, I've added the feature to hold a signed book and convert it to a yml file running a command.

It can be done by running the command:

/vb create <bookName> <command> [<permission>/none]

This will create a .yml file for the book and register the command, For 1.18 versions, command won't be registered in tab completion until server reload (it will still work just won't show up in tab complete!). For permission, you can just put "none" in the command if you don't want a permission for the book. Example:
/vb create TestBook testcommand none

I hope you enjoy the update!