Define repo-specific labels.
Define repo-specific labels.

This commit adds a `.appends/.github/labels.yml` file, which contains the repo-specific labels. This file will automatically be combined with the Exercism-wide labels defined in https://github.com/exercism/org-wide-files/blob/main/global-files/.github/labels.yml to form the `.github/labels.yml` file.

NobbZ/xerlang