Documenting PoSt Proving Set Computation

[nicola]

@whyrusleeping mentioned that he has some documentation that needs to have a proving set (the set of commRs) to be really small and efficient to calculate.

[whyrusleeping]

I don't think I ever said it was small and efficient. It's just maintaining a big list. Also, i'm pretty sure that this solution is not something we can launch with.

[nicola]

I remember we had a way to compress the indexes of the commRs (?), just leaving this issue here, feel free to tag as you want

[mhammersley]

Matching to Filecoin Research Prioritization list

[whyrusleeping]

currently the proving set is just a bit list of sectors stored in the miner actor. If we decide this doesnt scale well, we can re-evaluate as a followup 'scale X better' issue, but for now i'm gonna mark this as done