Document GenesisProtocol parameters

[Arc documentation](https://daostack.github.io/arc/generated_docs/VotingMachines/GenesisProtocol/#parametersbytes32) says nothing about the function of any of the GenesisProtocol parameters. The solidity code contains cursory documentation, but not sufficient. It would be better if edited for English, provided units (like Wei, seconds, etc), and described all the referenced concepts, for example "threshold" and "quite ending".