🤖 CODE_OF_CONDUCT: tweak email contact information

[exercism-bot]

Upstream: exercism/org-wide-files@f28daf625fa3

---

👁 Tracking issue: exercism/org-wide-files#229

[ee7]

Self-assigned because I'd prefer the commit title to be:

CODE_OF_CONDUCT: tweak email contact information (#138)

and commit body:

Upstream: https://github.com/exercism/org-wide-files/commit/f28daf625fa3

The body of the commit on the PR branch points to a less useful commit.

I prefer to avoid:

🤖 Sync org-wide files to upstream repo

because I like the first more than the second:

• https://github.com/exercism/configlet/commits?author=exercism-bot
• https://github.com/exercism/ruby/commits?author=exercism-bot