ECS worker setup guide improvements

[jeanluciano]

Closes #394

Example

Graph updated to used Prefect colors, open to different color values:

%%{
  init: {
    'theme': 'base',
    'themeVariables': {
      'primaryColor': '#2D6DF6',
      'primaryTextColor': '#fff',
      'lineColor': '#FE5A14',
      'secondaryColor': '#E04BF0',
      'tertiaryColor': '#fff'
    }
  }
}%%
graph TB

  subgraph ecs_cluster[ECS cluster]
    subgraph ecs_service[ECS service]
      td_worker[Worker task definition] --> |defines| prefect_worker((Prefect worker))
    end
    prefect_worker -->|kicks off| ecs_task
    fr_task_definition[Flow run task definition]

    subgraph ecs_task["ECS task execution"]
    style ecs_task text-align:center,display:flex

    flow_run((Flow run))

    end
    fr_task_definition -->|defines| ecs_task
  end

  subgraph prefect_cloud[Prefect Cloud]
    subgraph prefect_workpool[ECS work pool]
      workqueue[Work queue]
    end
  end

  subgraph github["ECR"]
    flow_code{{"Flow code"}}
  end
  flow_code --> |pulls| ecs_task
  prefect_worker -->|polls| workqueue
  prefect_workpool -->|configures| fr_task_definition

Screenshots

Checklist

• [ x ] References any related issue by including "Closes #" or "Closes ".
  • If no issue exists and your change is not a small fix, please create an issue first.
• [ ] Includes tests or only affects documentation.
• [ ] Passes pre-commit checks.
  • Run pre-commit install && pre-commit run --all locally for formatting and linting.
• [ ] Includes screenshots of documentation updates.
  • Run mkdocs serve view documentation locally.

[kevingrismore]

There's a reference on line 5 to "Prefect 2" which I think we can change to just "Prefect"