Reward Tree v10: Errata and Clarifications

[haloooloolo]

• changes interval variable name to currentIndex to match previous reference to the reward interval
• specifically states that bonus commission eligibility is also subject to standard smoothing pool eligibility criteria
• specifically states that no bonus should be awarded if eligibleStartTime ≥ eligibleEndTime
• removes getMinipoolBonus function to simplify the spec as it was only called once
• changes getTotalNodeFee arguments from baseFee, percentOfBorrowedETH to minipoolFee, minipoolBond
• fixes typo: totalEthForMinipool -> totalEthForMinipools
• removes beacon balance queries from consensus income calculation due to performance issues

[Valdorff]

Looks good to me, though I'm not an expert here.

Written by @haloooloolo. @jshufro agreed it was ready to be merged. I did not see an explicit go-ahead from @xrchz (the other person active on reward tree work), but I have seen work on their end with this spec and no complaints.