[STAR-2983] Update info about non-billable accounts to reflect recent category changes.
In the context of STAR-3920 we updated the categorization of non-billable cell and non-billable non-cell accounts; see this comment for details.
This PR updates the handbook to reflect the changes.
It also fixes some typos and removes some outdated information found along the way.
Testing
- Verify that there are no formatting issues in rendered changes.
Tickets
Reviewers
Edited by Tim Krones