[Docs] Document the dataset health management page

[mdbirnstiehl]

Figma design here

Project ticket: https://github.com/elastic/observability-dev/issues/2887

Project Page: https://github.com/orgs/elastic/projects/1184/views/12

Because the system is set to accept all logs, users need to be able to monitor their datasets to find and fix any issues that occur in their log data. The information found on this page will serve as a foundation for the user to monitor the overall health of their datastreams and find any datastreams with issues and fix them. The datastream quality page will have two iterations, with the first being mostly informative and the second providing a flyout where the user can take action.

The focus shouldn’t be documenting the UI, though we can give an overview. It should be more on that data provided and why this data is useful.

Additional information and collaboration happening in this document.

[mdbirnstiehl]

elastic/kibana#170611 - issue to monitor for when the page will be available to users