add doc

  in gocd, use the python-app pipeline template to automate stages and jobs.

** 2018-05-02 workflow for v1.2.0+

- create project on dev node.

- create gitlab repo by init-gitlab

- dev on dev node.

  make test

  make run

- when ready to push to production.

  update deb-scripts if necessary

  update ./utils/build-deb if necessary

  update app.yaml if necessary

- on gitlab, add gocd as deploy key

- on gocd, create new pipeline for the project.

  use python-app template.

  // these two step should be automated.

- on dev node, git push

  now you will see gocd start testing, building docker image and push it.

  when first stage is green, click approval to deploy to production.

- to upgrade project, make commits, and push to gitlab, the rest will follow.

  click approval to deploy to production.

* current							      :entry:

** 

** 2016-09-08 support updating site file, deb scripts etc after project is generated.