v0.35.2 — state the Docker Hub token scope

dockerhub_token needs Read, Write AND Delete. Pushing an image only needs Write,
but writing repository metadata sits behind the same scope Docker Hub uses for
Delete and there is no tier between them, so a Read/Write token pushes fine and
then fails every metadata call with 'access denied: insufficient scope'.

Nothing here ever issues a DELETE. Docs only; no behaviour change.