The structure of this header has never been specified in the docs and has
been a pain point for those who have tried to get registry authentication
to work during builds. This Patch *finally* adds a description of JSON
object which should be base64-url-safe-encoded and used as the value of
the X-Registry-Config HTTP request header during `POST /build`.
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
Upstream-commit: 61de9629799094d579068899ca407d5034183e0f
Component: engine
186d7f8a00