The `aio` commit message scope was renamed to `docs-infra` (which is
more descriptive) in #24295. Although it has been removed from the
documentation, the legacy `aio` scope was kept in the [list of valid
scopes][1] to cater for in-flight PRs that already used it. As a result,
it still shows up as a recommended, valid scope in the error message
shown when commit message validation fails during `git commit`. This is
misleading, especially for new contributors.
Since we have been "manually" discouraging people from using `aio`,
there should be no open PRs by now (and if there are, they should be
changed to `docs-infra`), so it is safe to remove it from the list of
allowed scopes.
Related discussion:
https://github.com/angular/angular/pull/32273#pullrequestreview-279767931
[1]: https://github.com/angular/angular/blob/3df54be9e/tools/validate-commit-message/commit-message.json#L16
PR Close#32341