Just an FYI to whoever is responsible for this, the "Implementation Notes" that are posted at the top of the page here in the support site:
https://knowledge.opentext.com/knowledge/llisapi.dll?func=ll&objId=67789539&objAction=browse&viewType=1
are not included on the developer.opentext.com site here, even though there are references to it in the documentation:
https://developer.opentext.com/webaccess/#url=/awd/resources/apis/cs-rest-api-for-cs-16-s#!/categories/updateCategory_put_8&tab=501
Also, the documentation on knowledge.opentext.com just looks more updated. Compare the sections on PUT/Update a Category.