Instructions exist that often refer to docsite but never define which of the directories is the docsite. Is it the built-docs directory or the built-docs/rst directory, or some other directory, perhaps built-docs/build?
What is “it” in your question? The extra docs material must be in docs/docsite/ (like config.yml, extra-docs.yml, links.yml, and rst/ for extra documentation source files). Where you place the rendered result or the build scripts for the docsite is up to you. It can be whereever you want in the filesystem.