Updated maturities for Manage: Audit management and authentication

This MR does two things:

• Updates two Manage categories, Audit Management and Authentication/Authorization, to Viable. Based on the definition on that maturity page, both of these features are better than minimal (but can't be considered Complete).
• Updates the FY20 OKR page to reflect the moving of two Minimal categories to Viable by reducing the number of Minimal -> Viable categories and increasing the number of Viable -> Complete.