util/docker/doc.coreboot.org/Dockerfile: Use alpine:3.8, Sphinx 1.7

With Alpine base, use pip to install Sphinx 1.7 and Sphinx-autobuild
Alpine, a 4.5MB base, is used over Debian Stable, 101MB, to cut down the
total size of the docker image.

Change-Id: I53f246206458b1de34cd7f3a42481b91ca285ff0
Signed-off-by: Tom Hiller <thrilleratplay@gmail.com>
Reviewed-on: https://review.coreboot.org/28211
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

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

@@ -1,3 +1,32 @@
-How to use:
+# doc.coreboot.org
+ Docker container for generating and developing documentation for doc.coreboot.org
 
-docker run --rm -v $path-to-coreboot.git:/data-in:ro -v $path-to-html-output:/data-out $image
+**NOTE**: All paths are from the base of the coreboot git repo.
+
+### Build
+
+```sh
+  docker build --force-rm -t "doc.coreboot.org" "$PWD/util/docker/doc.coreboot.org/"
+```
+
+### Generating production HTML
+
+```sh
+# To ensure the output directory is given the correct permissions, make sure to
+# created it before running docker the first time.
+mkdir -p "$PWD/Documentation/_build/"
+
+docker run -it --rm \
+           --user "$(id -u):$(id -g)" \
+           -v "$PWD/:/data-in/:ro" \
+           -v "$PWD/Documentation/_build/:/data-out/" \
+           doc.coreboot.org
+```
+
+### live reloaded with web server
+On the host machine, open a browser to the address http://0.0.0.0:8000
+```sh
+docker run -it --rm \
+           --net=host -v "$PWD/:/data-in/:ro" \
+           doc.coreboot.org livehtml
+```