Improve CoC for events

[emmyft]

We are now hosting events like the open science coffee, with many people within and outside of the community, so it'll be good to specify who and to what interactions the CoC applies to, the duration for reporting, where can they report, etc.

• [ ] draft changes as an addendum
• [ ] let community review them

[emmyft]

Related to improving the CoC - Thanks to Yo we've now got a more reuser-friendly CoC and a CoC template repo 🎉

@all-contributors please add @yochannah for ideas

[allcontributors[bot]]

@emmyft

I've put up a pull request to add @yochannah! :tada: