Refactor Autodeploy docs

- Add a how it works section where Herokuish is mentioned
- Make the notes more apparent
- Merge the postgres variables section with its parent

doc/ci/autodeploy/index.md

 # Auto deploy
 
-> [Introduced][mr-8135] in GitLab 8.15.
-> Auto deploy is an experimental feature and is not recommended for Production use at this time.
-> As of GitLab 9.1, access to the container registry is only available while the Pipeline is running. Restarting a pod, scaling a service, or other actions which require on-going access will fail. On-going secure access is planned for a subsequent release.
+>**Notes:**
+- [Introduced][mr-8135] in GitLab 8.15.
+- Auto deploy is an experimental feature and is not recommended for Production
+  use at this time.
+- As of GitLab 9.1, access to the Container Registry is only available while
+  the Pipeline is running. Restarting a pod, scaling a service, or other actions
+  which require on-going access will fail. On-going secure access is planned for
+  a subsequent release.
 
 Auto deploy is an easy way to configure GitLab CI for the deployment of your
 application. GitLab Community maintains a list of `.gitlab-ci.yml`
@@ -11,9 +16,19 @@ powering them. These scripts are responsible for packaging your application,
 setting up the infrastructure and spinning up necessary services (for
 example a database).
 
-You can use [project services][project-services] to store credentials to
-your infrastructure provider and they will be available during the
-deployment.
+## How it works
+
+The Autodeploy templates are based on the [kubernetes-deploy][kube-deploy]
+project which is used to simplify the deployment process to Kubernetes by
+providing intelligent `build`, `deploy` and `destroy` commands which you can
+use in your `.gitlab-ci.yml` as-is. It uses [Herokuish](https://github.com/gliderlabs/herokuish),
+which uses [Heroku buildpacks](https://devcenter.heroku.com/articles/buildpacks)
+to do some of the work, plus some of GitLab's own tools to package it all up. For
+your convenience, a [Docker image][kube-image] is also provided.
+
+You can use the [Kubernetes project service](../../user/project/integrations/kubernetes.md)
+to store credentials to your infrastructure provider and they will be available
+during the deployment.
 
 ## Quick start
 
@@ -26,30 +41,28 @@ The list of supported auto deploy templates is available in the
 
 ## Configuration
 
+>**Note:**
+In order to understand why the following steps are required, read the
+[how it works](#how-it-works) section.
+
+To configure Autodeploy, you will need to:
+
 1. Enable a deployment [project service][project-services] to store your
-credentials. For example, if you want to deploy to OpenShift you have to
-enable [Kubernetes service][kubernetes-service].
-1. Configure GitLab Runner to use Docker or Kubernetes executor with
-[privileged mode enabled][docker-in-docker].
+   credentials. For example, if you want to deploy to OpenShift you have to
+   enable [Kubernetes service][kubernetes-service].
+1. Configure GitLab Runner to use the
+   [Docker or Kubernetes executor](https://docs.gitlab.com/runner/executors/) with
+   [privileged mode enabled][docker-in-docker].
 1. Navigate to the "Project" tab and click "Set up auto deploy" button.
    ![Auto deploy button](img/auto_deploy_button.png)
 1. Select a template.
   ![Dropdown with auto deploy templates](img/auto_deploy_dropdown.png)
 1. Commit your changes and create a merge request.
 1. Test your deployment configuration using a [Review App][review-app] that was
-created automatically for you.
+   created automatically for you.
 
 ## Using the Kubernetes deploy example project with Nginx
 
-The Autodeploy templates are based on the [kubernetes-deploy][kube-deploy]
-project which is used to simplify the deployment process to Kubernetes by
-providing intelligent `build`, `deploy` and `destroy` commands which you can
-use in your `.gitlab-ci.yml` as-is. It uses Heroku'ish build packs to do some
-of the work, plus some of GitLab's own tools to package it all up. For your
-convenience, a [Docker image][kube-image] is also provided.
-
----
-
 A simple example would be the deployment of Nginx on Kubernetes.
 Consider a `nginx-deployment.yaml` file in your project with contents:
 
@@ -77,7 +90,8 @@ spec:
 ```
 
 The important part is where we set up `app: __CI_ENVIRONMENT_SLUG__`. As you'll
-see later this is replaced by the [`CI_ENVIRONMENT_SLUG` env variable][variables].
+see later this is replaced by the
+[`CI_ENVIRONMENT_SLUG` env variable](../variables/README.md#predefined-variables-environment-variables).
 
 The `.gitlab-ci.yml` would be:
 
@@ -118,7 +132,7 @@ Next, we replace `__CI_ENVIRONMENT_SLUG__` with the content of the
 Finally, the Nginx pod is created from the definition of the
 `nginx-deployment.yaml` file.
 
-## Private Project Support
+## Private project support
 
 > Experimental support [introduced][mr-2] in GitLab 9.1.
 
@@ -126,7 +140,7 @@ When a project has been marked as private, GitLab's [Container Registry][contain
 
 After the pipeline completes, Kubernetes will no longer be able to access the container registry. Restarting a pod, scaling a service, or other actions which require on-going access to the registry will fail. On-going secure access is planned for a subsequent release.
 
-## PostgreSQL Database Support
+## PostgreSQL database support
 
 > Experimental support [introduced][mr-8] in GitLab 9.1.
 
@@ -134,27 +148,13 @@ In order to support applications that require a database, [PostgreSQL][postgresq
 
 PostgreSQL provisioning can be disabled by setting the variable `DISABLE_POSTGRES` to `"yes"`.
 
-### PostgreSQL Variables
+The following PostgreSQL variables are supported:
 
 1. `DISABLE_POSTGRES: "yes"`: disable automatic deployment of PostgreSQL
 1. `POSTGRES_USER: "my-user"`: use custom username for PostgreSQL
 1. `POSTGRES_PASSWORD: "password"`: use custom password for PostgreSQL
 1. `POSTGRES_DB: "my database"`: use custom database name for PostgreSQL
 
-[mr-8135]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8135
-[mr-2]: https://gitlab.com/gitlab-examples/kubernetes-deploy/merge_requests/2
-[mr-8]: https://gitlab.com/gitlab-examples/kubernetes-deploy/merge_requests/8
-[project-settings]: https://docs.gitlab.com/ce/public_access/public_access.html
-[project-services]: ../../user/project/integrations/project_services.md
-[auto-deploy-templates]: https://gitlab.com/gitlab-org/gitlab-ci-yml/tree/master/autodeploy
-[kubernetes-service]: ../../user/project/integrations/kubernetes.md
-[docker-in-docker]: ../docker/using_docker_build.md#use-docker-in-docker-executor
-[review-app]: ../review_apps/index.md
-[kube-image]: https://gitlab.com/gitlab-examples/kubernetes-deploy/container_registry "Kubernetes deploy Container Registry"
-[kube-deploy]: https://gitlab.com/gitlab-examples/kubernetes-deploy "Kubernetes deploy example project"
-[container-registry]: https://docs.gitlab.com/ce/user/project/container_registry.html
-[postgresql]: https://www.postgresql.org/
-
 ## Auto Monitoring
 
 > Introduced in [GitLab 9.5](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/13438).
@@ -179,3 +179,18 @@ If you have installed GitLab using a different method:
 1. [Deploy Prometheus](../../user/project/integrations/prometheus.md#configuring-your-own-prometheus-server-within-kubernetes) into your Kubernetes cluster
 1. If you would like response metrics, ensure you are running at least version 0.9.0 of NGINX Ingress and [enable Prometheus metrics](https://github.com/kubernetes/ingress/blob/master/examples/customization/custom-vts-metrics/nginx/nginx-vts-metrics-conf.yaml).
 1. Finally, [annotate](https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/) the NGINX Ingress deployment to be scraped by Prometheus using `prometheus.io/scrape: "true"` and `prometheus.io/port: "10254"`.
+
+[mr-8135]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8135
+[mr-2]: https://gitlab.com/gitlab-examples/kubernetes-deploy/merge_requests/2
+[mr-8]: https://gitlab.com/gitlab-examples/kubernetes-deploy/merge_requests/8
+[project-settings]: https://docs.gitlab.com/ce/public_access/public_access.html
+[project-services]: ../../user/project/integrations/project_services.md
+[auto-deploy-templates]: https://gitlab.com/gitlab-org/gitlab-ci-yml/tree/master/autodeploy
+[kubernetes-service]: ../../user/project/integrations/kubernetes.md
+[docker-in-docker]: ../docker/using_docker_build.md#use-docker-in-docker-executor
+[review-app]: ../review_apps/index.md
+[kube-image]: https://gitlab.com/gitlab-examples/kubernetes-deploy/container_registry "Kubernetes deploy Container Registry"
+[kube-deploy]: https://gitlab.com/gitlab-examples/kubernetes-deploy "Kubernetes deploy example project"
+[container-registry]: https://docs.gitlab.com/ce/user/project/container_registry.html
+[postgresql]: https://www.postgresql.org/
+