I went through the shipped document from csui-sdk-16.0.3.zip. I admit that it has so much info to absorb. But anyway, you may already notice that the following documents are missing. I quickly checked in the csui-doc-16.0.3.zip; I think it appears the same problem. So for your information, here are the lists:
Cannot GET /doc/csui/integration/folderbrowser/folderbrowser.widget/index.html
Cannot GET /doc/csui/integration/target.picker/target.picker/index.html
Cannot GET /doc/csui/utils/contexts/context/index.html
Cannot GET /doc/csui/utils/contexts/page/page.context/index.html
Cannot GET /doc/csui/utils/contexts/portal/portal.context/index.html
Cannot GET /doc/csui/utils/contexts/browsing/browsing.context/index.html