ENH: Address Trishank's review comments

[SantiagoTorres]

Although this diff seems minimal, I tried to address the following comments from @trishankkarthik:

Unanswered

• There are too many terms upfront
• Sections 2-3 are particularly redundant.
• More picutres and diagrams are necessary (ASK)
• POSIX timestamps
• Point 8 of minor readability issues (ask trishank)
• Why is there mention of private keys in the metadata?
• Commands sound dangerous, are clients expected to run arbitrary commands? (ASK/Debate/FAQ)
• What about rollback attacks? (Elaborate/question)

Answered/FIXED.

• Disambiguate between functionaries and parties
• Disambiguate between actors and roles
• The website has no examples see updated website
• Typos and style mismatches on section headers
• Some mock sha256sums match when they shouldn't

[lukpueh]

I transferred the remaining items to #14. Merging/closing here.