Connect sign-up to Sendico Facts intake (#46)

backend/product/config.example.yml

@@ -9,6 +9,13 @@ database:
     uri_env: SXCHNGE_MONGO_URI
     database: sxchnge
 api:
+  # Optional public Sendico facts integration. Enable with provisioned values;
+  # omit this block to retain local-only sign-up. See docs/signup-facts.md.
+  # sendico:
+  #   api_url: https://sendico.example/api/v1
+  #   organization_ref: <sxchnge-organization-object-id>
+  #   source_account_ref: <integration-account-object-id>
+  #   token_file: /run/sxchnge/sendico-token
   # Optional: omit for v1 at SXCHNGE_API_ENDPOINT; [] disables application APIs.
   # versions:
   #   - version: v1