docs: remove outdated README

The instructions in the file were outdated, and after removing them,
nothing really substantial was remaining, so let's just remove the
file for now.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/README.md

@@ -1,36 +0,0 @@
-# The non-reference docs have been moved!
-
-<!-- This file is maintained within the docker/cli GitHub
-     repository at https://github.com/docker/cli/. Make all
-     pull requests against that repo. If you see this file in
-     another repository, consider it read-only there, as it will
-     periodically be overwritten by the definitive file. Pull
-     requests which include edits to this file in other repositories
-     will be rejected.
--->
-
-The documentation for Docker Engine has been merged into
-[the general documentation repo](https://github.com/docker/docker.github.io).
-
-See the [README](https://github.com/docker/docker.github.io/blob/master/README.md)
-for instructions on contributing to and building the documentation.
-
-If you'd like to edit the current published version of the Engine docs,
-do it in the master branch here:
-https://github.com/docker/docker.github.io/tree/master/engine
-
-If you need to document the functionality of an upcoming Engine release,
-use the `vnext-engine` branch:
-https://github.com/docker/docker.github.io/tree/vnext-engine/engine
-
-The reference docs have been left in docker/docker (this repo), which remains
-the place to edit them.
-
-The docs in the general repo are open-source and we appreciate
-your feedback and pull requests!
-
-# Generate docs
-
-```shell
-$ make -f docker.Makefile yamldocs
-```