[Task]: Document types of work in addons-server

[KevinMind]

Description

We utilize different vehicles to execute work in addons-server. There are utility methods, tasks, cron jobs, management commands, model methods etc. All executing business logic in some capacity. We should document the best practices we've discovered over the years and sensible guard rails to ensure quality is maintained.

Acceptance Criteria

  ### Acceptance Criteria
  - [ ] 

Checks

• [X] If the issue is ready to work on, I have removed the "needs:info" label.

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