Adds a Knowledge Article Category

If you have trouble with creating a Knowledge Article Category, try creating Knowledge Article Categories via the web interface, and then access those Knowledge Article Categories via the API. This way you can see examples of the fields and sub-elements attached to the Knowledge Article Category. 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.