[docs] Fix operator docs no longer being built and published

.buildkite/docs-docker-compose.yml

@@ -3,7 +3,7 @@ services:
   docs:
     build:
         context: ./
-        dockerfile: ../site/content/docs/Dockerfile
+        dockerfile: ../docker/docs/Dockerfile
     volumes:
       - ../:/go/src/github.com/m3db/m3
       - $SSH_AUTH_SOCK:/ssh-agent

docker/docs/Dockerfile

@@ -0,0 +1,17 @@
+# Dockerfile for building docs is stored in a separate dir from the docs,
+# otherwise the generated site will unnecessarily contain the Dockerfile
+
+FROM python:3.5-alpine
+LABEL maintainer="The M3DB Authors <[email protected]>"
+
+WORKDIR /m3db
+EXPOSE 8000
+
+# mkdocs needs git-fast-import which was stripped from the default git package
+# by default to reduce size
+RUN pip install \
+    mkdocs==0.17.3 \
+    pymdown-extensions==6.0 \
+    mkdocs-material==2.7.3
+RUN apk add --no-cache git-fast-import openssh-client
+ENTRYPOINT [ "/bin/ash", "-c" ]

site/content/docs/how_to/kubernetes.md

@@ -4,10 +4,10 @@ weight: 3
 ---
 
 
-**Please note:** If possible _PLEASE USE THE OPERATOR_ to deploy to Kubernetes if you
+**Please note:** If possible _[PLEASE USE THE OPERATOR](https://operator.m3db.io/)_ to deploy to Kubernetes if you
 can. It is a considerably more streamlined setup.
 
-The operator leverages [custom resource definitions](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
+The [operator](https://operator.m3db.io/) leverages [custom resource definitions](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
 (CRDs) to automatically handle operations such as managing cluster topology.
 
 The guide below provides static manifests to bootstrap a cluster on Kubernetes and should be considered