Add a .appends/.github/labels.yml file. (exercism#1030)

The `.appends/.github/labels.yml` file contains all the labels that are currently used in this repo.
The `.github/labels.yml` file will contain the full list of labels that this repo can use, which will be a combination of the `.appends/.github/labels.yml` file and a centrally-managed `labels.yml` file.
We'll automatically sync any changes, which allows us to guarantee that all the track repositories will have a pre-determined set of labels, augmented with any custom labels defined in the `.appends/.github/labels.yml` file.

.appends/.github/labels.yml

@@ -0,0 +1,8 @@
+# ----------------------------------------------------------------------------------------- #
+# These are the repository-specific labels that augment the Exercise-wide labels defined in #
+# https://github.com/exercism/org-wide-files/blob/main/global-files/.github/labels.yml.     #
+# ----------------------------------------------------------------------------------------- #
+
+- name: "bug?"
+  description: ""
+  color: "eb6420"