Prop 75: [SIPS-070] Proposal to add DAI Savings Rate Support to Real Yield USD

This text proposal is to add DSR support to RYUSD. If accepted, a strategist call to the Cellar will enact the change.

See the corresponding forum post for more details: https://community.sommelier.finance/t/sips-070-upcoming-proposal-to-add-dai-savings-rate-support-to-real-yield-usd/1169