Adds a Knowledge Article Folder

If you have trouble with creating a Knowledge Article Folder, try creating Knowledge Article Folders via the web interface, and then access those Knowledge Article Folders via the API. This way you can see examples of the fields and sub-elements attached to the Knowledge Article Folder. A common source of problems during write/update request is caused when users omit required fields, or insert invalid data in a field (e.g. reference a CATEGORY_ID that does not exist in the user's Insightly instance.