Bug fix PRs to tooling don't have a sensible/obvious changelog entry type

For example, https://github.com/matrix-org/matrix-spec/pull/1368 - normally this would be an internal bug fix, but the closest we have is "clarification" or "feature". Neither particularly cover the task well.

Review the changelog entry types used by the tooling and compare them with the bug-fix example in pull request 1368. Define what entry type should represent internal tooling bug fixes, then verify that the tooling accepts and renders the new classification consistently.

Written by the indexing model from the issue text.