NETWORK-501 manual docker build process (#55)

update documentation

example/Dockerfile-envoy-image

@@ -0,0 +1,6 @@
+FROM ubuntu:14.04
+
+ADD build/source/exe/envoy /usr/local/bin/envoy
+RUN apt-get update && apt-get install -y \
+    curl \
+    python-pip

example/README.md

@@ -1,2 +1,38 @@
 To learn about this sandbox and for instructions on how to run it please head over
 to the envoy docs
+
+### Building the Docker image
+
+The `lyft/envoy` image is a docker image made using `build-envoy/Dockerfile-envoy`
+it copies a precompiled envoy binary into a docker image, and installs `curl`
+and `pip`.
+
+The following steps guide you through building your own envoy binary, and
+putting that in a clean ubuntu container.
+
+#### Step 1: Build Envoy
+
+Using `lyft/envoy-buld` you will compile envoy.
+This image has all software needed to build envoy. From your envoy directory:
+
+```shell
+$ pwd
+src/envoy
+$ docker run -t -i -v <SOURCE_DIR>:/source lyft/envoy-build:latest /bin/bash -c "cd /source && ci/do_ci.sh normal"
+```
+
+That command will take some time to run because it is compiling an envoy binary.
+
+#### Step 2: Build image with only envoy binary
+
+In this step we'll build an image that only has the envoy binary, and none
+of the software used to build it.
+
+```shell
+$ pwd
+src/envoy/
+$ docker build -f example/Dockerfile-envoy-image -t envoy .
+```
+
+Now you can use this `envoy` image to build the demo if you change the `FROM`
+line in `Dockerfile-frontenvoy` and `Dockerfile-service`