Document how template authors can reexecute their jobs with locally patch scripts

[gberche-orange]

Is your feature request related to a problem? Please describe.

The CI/CD workflow process provided by COA is great when complex commands need to be invoked. However, sometimes for small fixes in a shell script (deploy.sh, post-deploy.sh), service authors would like to fix and retry just this task. The current cycle time for the sync-feature branch often long (5-10 mins)

Describe the solution you'd like

Document a way to use fly hijack to run a task shell script using a locally modified version of a hook.

Associated pseudo code follows:

• fly hijack -u build-url -c CMD
• CMD is :
  • install rsync binary if necessary
  • rsync remote container dir with local development version
  • execute coa pipeline task shell:
    

    cf-ops-automation/concourse/tasks/post_bosh_deploy.yml

    Line 15 in a16cdd7

    path: scripts-resource/concourse/tasks/post_deploy/run.sh

Describe alternatives you've considered

fly hijack + vi script to fix it + execute script

[gberche-orange]

Somewhat related/similar pattern documented into https://github.com/pivotalservices/concourse-pipeline-samples/tree/master/concourse-pipeline-hacks/fly-execute