message: Add note about the API server command
diff: @@ -61,3 +61,8 @@ npm run cli -- -pk user1-private.pem -fetch <content_id>
  A REST API is provided for integration from another application, such as legacy shipping or ERP system, in the [`/api/`](api/README.md) directory.
  Examples for using the REST API is in the [`/example`](example/README.md) directory.
  +
  +To start the API server:
  +```
  +npm run api
  +```
  