update default value for --env SMTP_DOMAINS

docker/README.md

@@ -117,7 +117,7 @@ You can specify the following environment variables when issuing `docker run` co
 | `MYSQL_DSN` | string | `'root@tcp(mysql)/tinode'` | MySQL [DSN](https://github.com/go-sql-driver/mysql#dsn-data-source-name). |
 | `PLUGIN_PYTHON_CHAT_BOT_ENABLED` | bool | `false` | Enable calling into the plugin provided by Python chatbot |
 | `RESET_DB` | bool | `false` | Drop and recreate the database. |
-| `SMTP_DOMAINS` | string | `[]` | White list of email domains; when non-empty accept emails from these domains only  (email verification). |
+| `SMTP_DOMAINS` | string |  | White list of email domains; when non-empty accept emails from these domains only  (email verification). |
 | `SMTP_HOST_URL` | string | `'http://localhost:6060/'` | URL of the host where the webapp is running (email verification). |
 | `SMTP_PASSWORD` | string |  | Password to use for authentication with the SMTP server (email verification). |
 | `SMTP_PORT` | number |  | Port number of the SMTP server to use for sending verification emails, e.g. `25` or `587`. |