adopt a code of conduct

[zingale]

We should adopt a code of conduct for our project. I adapted the Astropy code of conduct (which is CC licensed). My intention is for this code of conduct to cover the entire AMReX-Astro project, which means we want to get a sign-off from Castro, Nyx, and MAESTROeX developers. We'll use this issue for the Castro developers to discuss it.

https://github.com/AMReX-Astro/organization/pull/1

[zingale]

checkboxes below are for the current "core" developers, but everyone is welcome to comment. Please check off your name if you agree to adopting the code of conduct. Please comment in the PR if you have suggestions for improvement to the code of conduct.

• [ ] Ann Almgren (@asalmgren)
• [ ] Maria Barrios Sazo (@guadabsb15)
• [ ] John Bell (@jbbel)
• [ ] Alice Harpole (@harpolea)
• [ ] Max Katz (@maxpkatz)
• [ ] Andy Nonaka (@ajnonaka)
• [ ] Jean Sexton (@jmsexton03)
• [x] Don Willcox (@dwillcox)
• [ ] Weiqun Zhang (@WeiqunZhang)
• [x] Michael Zingale (@zingale)

[zingale]

this has been done