Revisions of the Reviewing Code and Code of Conduct

[Matthias Koeppe]

As suggested in the thread "Policy for disputed PRs: discussion" (https://groups.google.com/g/sage-devel/c/rDM3WDHnJkM/m/Z5Bqxyv1AQAJ), we should also amend our Reviewing Code (https://doc.sagemath.org/html/en/developer/review.html). 

Additionally I propose to amend our Code of Conduct (https://github.com/sagemath/sage/blob/develop/CODE_OF_CONDUCT.md) to make it easier to understand. As a first step, in https://github.com/sagemath/sage/pull/36844, I propose to add some more concrete examples of problematic conduct.

A positive and civil discussion is very welcome, both here for the general topic and on the PR regarding the specific additions.

Matthias

[Matthias Koeppe]

Another proposed change: https://github.com/sagemath/sage/pull/37054 ("Do not send people to sage-flame")