Make product API versions independently installable

backend/product/config.example.yml

@@ -9,6 +9,10 @@ database:
     uri_env: SXCHNGE_MONGO_URI
     database: sxchnge
 api:
+  # Optional: omit for v1 at SXCHNGE_API_ENDPOINT; [] disables application APIs.
+  # versions:
+  #   - version: v1
+  #     path: /api/v1
   middleware:
     domain_env: SXCHNGE_DOMAIN
     api_endpoint_env: SXCHNGE_API_ENDPOINT