feat(redis): add ansible role

roles/redis/README.md

@@ -37,3 +37,11 @@ redis_container_volumes:
   - "/path/to/socket/on/host/redis.sock:{{ redis_container_socket }}:z"
 redis_config_unixsocket: "{{ redis_container_socket }}"
 ```
+
+## Container specific information
+
+Redis publishes their official container image in both a debian-based and an
+alpine-based variant. Which image should be used can be configured in
+`redis_container_image_flavour`, which defaults to `alpine`, which is smaller
+in size but also includes less related / debugging tools. To use the debian-
+based image, unset the flavour using `redis_container_image_flavour: ~`.