Broken link to code of conduct

[RoystonS]

The CODE_OF_CONDUCT.md file is referenced from a badge in README.md, which expects the file to be in the repository root, but the file is actually in the other directory. So the link is broken.

Either the link is wrong or the location is wrong. react-testing-library puts this file in the repo root.

Suggested solution:

Move CODE_OF_CONDUCT.md from other to the repo root?

(I was about to submit a PR for this, thinking the file was absent, but then I found it in other so I backed off and raised this issue instead.)

[kentcdodds]

Yeah, I think the file should be moved.

[RoystonS]

Fix in pull #175