PR #1451 added `CONTRIBUTING.md`, but the commit message guidelines
there conflict with the ones in `developer/code-quality.md`. Since
`CONTRIBUTING.md` is newer, presumably the guidelines there are what's
expected from new commits. But after removing that section from
`code-quality.md`, there's not much content left, so this commit just
deletes the file entirely.
Signed-off-by: Max Chernoff <git@maxchernoff.ca>