Write Documentation for the daily billing information

## Motivation
Users will want to know how to use the daily billing information in ColdFront.

## Completion Criteria
Document how to use daily billing in ColdFront

## Description
- [x] Review how it works on ColdFront
- [x] Write Draft
- [x] Get Draft reviewed
- [x] make updates based on reviews
- [ ] Post on NERC doc site


## Completion dates
Desired - 2025-12-10
Required - TBD
