Decrease DOT target APR 20%->13%. Increase Interlay fee 10%->15%

This proposal aims to increase Interlay protocol revenue by:

1. Decreasing the target APR (the jumpRate) for the Interlay DOT money market from 20% down to 13%.
2. Increasing the reserveFactor or Interlay protocol fee/spread on the DOT money market from 10% to 15%.

Why? The DOT native staking yield was around 18-20% when the DOT money market was originally created, but native staking yield has fallen to 11.4% APR. Additionally, we usually see the Interlay DOT market at an equilibrium APR of 8-13%. If we kept the DOT jumpRate at 20%, it would mean only about half of the loaned DOT is earning revenue for Interlay. Therefore, this proposal will decrease the jumpRate or target borrowing APR to 13% at a target utilization of 80%. Above 80% utilization the DOT borrowing rate will still increase up to a max of 50% APR.

In the picture below, the black line shows the change in the jumpRate while the green lines show how the DOT market is expected to continue to have the same borrowing rates after more of the available DOT is borrowed. This increases market utilization and therefore protocol revenue.

Secondly, note that there is $77.7k of qDOT backing in iBTC vaults. That means that $77k of the $385k loaned DOT is lent to create qDOT to run a vault and those qDOT vault operators aren't sensitive to the money market lending rate since they're primarily being paid by the vault rewards. Therefore, increase the Interlay cut of the borrowing APR rewards from 10% to 15% to increase Interlay protocol revenue slightly. This will only decrease the APY earned by DOT lenders and won't affect the APR paid by borrowers.

This proposal compensates me for 3 hours of research and discussion, testing with Chopsticks and creating the proposal.
3hrs x$100/hr = $300 = 19907 INTR at $0.01507/INTR