[CR] RES-1294: Deprecates Retrieve Usage calls in Reseller API

# Summary
Marked two api calls from Reseller API as deprecated because they do not work anymore.
 - Retrieving As-You-Go Usage
 - Retrieving Invoice Usage

## PR - Merge Checklist:
- [ ] CR’d 
- [x] README updated or N/A
- [ ] Repo/unit tests pass
- [x] Dependencies satisfied 
- [ ] Acceptance criteria verified by QE
- [ ] End to end testing completed by QE
 
## Dependencies: