reference: heroku moving to reference as now a commercial only service

Author: practicalli-johnny

docs/reference/continuous-integration/heroku/index.md

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+# CI: Heroku
+
+Heroku is a now only a commercial service without a developer environment.
+
+Practicalli is looking into other services as that are more developer friendly.
+
+
+## Heroku pipelines
+
+Using Heroku Pipelines the staging environment is promoted to production rather than being rebuilt
+
+![Heroku Pipeline concept - staging and production](https://raw.githubusercontent.com/jr0cket/developer-guides/master/heroku-pipelines-staging-production.png)
+
+The Heroku dashboard can be used to promote the application into production, once the staging application is signed off.
+
+![Heroku Pipeline banking-on-clojure](https://raw.githubusercontent.com/practicalli/graphic-design/live/continuous-integration/heroku/heroku-pipeline-banking-on-clojure.png)
+
+
+## Heroku Build process
+
+The build process starts when commits are pushed to Heroku, either directly or via a continuous integration service (eg. CircleCI).
+
+[![Heroku build process](https://raw.githubusercontent.com/jr0cket/developer-guides/gh-pages/heroku-deployment-process-simplified.png)](https://raw.githubusercontent.com/jr0cket/developer-guides/gh-pages/heroku-deployment-process-simplified.png)