util/docker: Add docker container that builds the sphinx documentation

It's what we use on coreboot.org to update
www.coreboot.org/Documentation

Change-Id: I6e5457d2e39a10f14fabd68bbb231a05e2f66f1d
Signed-off-by: Patrick Georgi <patrick@georgi.software>
Reviewed-on: https://review.coreboot.org/25869
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

util/docker/docs.coreboot.org/Dockerfile

@@ -0,0 +1,5 @@
+FROM debian:sid
+RUN apt-get update && apt-get install -y make python-sphinx python-recommonmark python-sphinx-rtd-theme
+USER nobody
+VOLUME /data-in /data-out
+ENTRYPOINT bash -c "cd /data-in/Documentation && make sphinx BUILDDIR=/tmp/build && rm -rf /data-out/* && mv /tmp/build/html/* /data-out/"

util/docker/docs.coreboot.org/README.md

@@ -0,0 +1,3 @@
+How to use:
+
+docker run --rm -v $path-to-coreboot.git:/data-in:ro -v $path-to-html-output:/data-out $image