[Proposal 0002] include a field for "how known" or credibility staking

[gvelez17]

So, sometimes i need to report somethign because its like, my personal stalker who threatened to harm me; or i know first hand something is harmful and why.

Other times i just kinda think its misinformation based on stuff I've read.

I'd like to be able to distinguish the two. Ideally, add optional fields:

how known: first hand, second hand, research
stake/confidence: how much am i willing to stake my credibility on this, from 0..100
source: optionally, uri of how i know this label applies

(this is all stuff from our reputation vocab http://cooperation.org/credentials/v1/ but of course don't need to use that, just think these fields would be useful)

[gvelez17]

Note, NOSTR has "confidence" in their proposal: https://github.com/nostr-protocol/nips/blob/master/32.md