Not sure where the best place(s) to do this is, e.g. README.md, CONTRIBUTING.md, in the RTD docs
and also remove/streamline any duplication of the conventions from the repos

At the same time can also add/reference Code of Conduct (#62)

• jupyter-book (Consolidate contributing/maintenance guidelines jupyter-book/jupyter-book#825)
• myst-nb
• myst-parser
• markdown-it-py
• markdown-it-myst (when moved)
• sphinx-book-theme
• sphinx-copybutton
• sphinx-togglebutton
• sphinx-panels
• sphinx-thebe
• thebelab (when moved)
• jupyter-cache
• myst-language-support

(also consider SUPPORT.md: https://github.blog/2017-07-20-support-file-support/)