Readme Clean Up Pass

[beaurancourt]

This shores up some common stuff I've noticed is out of date in our main repos:

• update/fix the links for the badges
• unify on 80-character lines
• update links to discord

I also dropped frdwrd as a person to contact about security vulnerabilities, since I didn't recognize the name

[mhluongo]

That's @prestwich. He's still a good backup to contact IMO, so I'd leave him unless he wants to be removed.

[prestwich]

that is me, but i have not opened keybase in a long time 😅 so probably go ahead and remove

[dimpar]

lgtm, but I don't think we contribute to this repo anymore.