docs: update CONTRIBUTING & COC

[vinckr]

• docs: update CONTRIBUTING.md + COC

Update CONTRIBUTING to add a section about adding new examples
update CONTRIBUTING to reflect the new Ory docs structure
update CONTRIBUTING with some language fixes and removing redundant info

update COC template from version 1.4. to 2.1

[kevgo]

I think the version of the Check format CI job is out of sync with the version of our shared Prettier config that this repo is formatted with. The repo uses ory-prettier-config v1.2.0, the CI job is stuck at v1.0.1.

#152 fixes this once and for all by making CI use the exact same Prettier configuration that npm run format uses.

[aeneasr]

LGTM but needs the conflicts to be resolved :)

[aeneasr]

https://github.com/ory/meta/runs/7000468600?check_suite_focus=true :)