Update Cedars user guides

The Quarterly Claims and Cost Effectiveness Tool CET user guides have been modernized; we could similarly modernize the Getting Started, Monthly Reports, and Budget & Application Filings user guides.

As a CEDARS user,
I want updated and modernized user guides for the Getting Started, Monthly Reports, and Budget & Application Filings sections,
So that I can access clearer, more user-friendly, and up-to-date documentation that aligns with the modernized guides for the Quarterly Claims and Cost Effectiveness Tool (CET).