Add Docker build capability (#9128)

* Add Dockerfile and make commands

* add background run option

* Expand on OSS attribution in new Dockerfile

* Begin adding README instructions for Docker

* Add new stage command

Dockerfile

@@ -0,0 +1,30 @@
+# Credit to Julien Guyomard (https://github.com/jguyomard). This Dockerfile
+# is essentially based on his Dockerfile at
+# https://github.com/jguyomard/docker-hugo/blob/master/Dockerfile. The only significant
+# change is that the Hugo version is now an overridable argument rather than a fixed
+# environment variable.
+
+FROM alpine:latest
+
+MAINTAINER Luc Perkins <lperkins@linuxfoundation.org>
+
+RUN apk add --no-cache \
+    curl \
+    git \
+    openssh-client \
+    rsync
+
+ARG HUGO_VERSION
+
+RUN mkdir -p /usr/local/src && \
+    cd /usr/local/src && \
+    curl -L https://github.com/gohugoio/hugo/releases/download/v${HUGO_VERSION}/hugo_${HUGO_VERSION}_linux-64bit.tar.gz | tar -xz && \
+    mv hugo /usr/local/bin/hugo && \
+    curl -L https://bin.equinox.io/c/dhgbqpS8Bvy/minify-stable-linux-amd64.tgz | tar -xz && \
+    mv minify /usr/local/bin && \
+    addgroup -Sg 1000 hugo && \
+    adduser -Sg hugo -u 1000 -h /src hugo
+
+WORKDIR /src
+
+EXPOSE 1313