Add best practices info for sub-tasks to JIRA Agile docs

As a SE I get a lot of customers not aware of the best practices for using sub-tasks in SCRUM. This subsequently causes a lot of problems for users going from classic to rapid boards as a lot of the way things are handled in the new versions are different. We have some fantastic general docs in https://www.atlassian.com/agile/ - can you please expand this to have information about best practices on sub-tasks?

For example, expanding on:

1. Create your user stories (aka tasks). Drag them and drop to the right version in the planning board.
2. Create sub-tasks for them with your estimates.
3. Add the stories to the sprint.
4. Complete the sprint - any sub-tasks that are not completed will continue to be tracked on the story (the parent) when it's returned back to the backlog after the sprint is complete.
5. The completed sub-tasks can be tracked with the Burndown chart.
6. If there are further sub-tasks to be completed, they can be scheduled in the next sprint when the story is added to it.