The changelog in the spec repo has to be updated manually for each PR but sometimes PR authors forget to do so. Relying on reviewers to catch this is error-prone.
In other OTel repos we use Github workflows to verify that the respective CHANGELOG.md was updated in PRs. For minor/editorial edits this check can be bypassed by applying a certain label.

Should we add the same for the spec repo as well?

See https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/.github/workflows/changelog.yml for an example.