[Standard] Proposing a new Code of Conduct

Hello,

For a long time, we have been thinking that the Code of Conduct we chose for the Standard for Public Code was not exactly what we wanted. So now we are proposing a new Code of Conduct.

The main features are that it is tailored for our audience, it's licensed CC 0 (like the standard) and it is very concise.

Check it out on https://github.com/publiccodenet/standard/pull/643