message: docs: Update config docs
diff: @@ -25,12 +25,15 @@ and then add the following in your root config:
  ```json
  {
  "@id": "urn:solid-server:default:MetadataParser",
  - "ParallelHandler:_handlers": [
  + "@type": "ParallelHandler",
  + "handlers": [
  { "@type": "MyNewParser" }
  ]
  }
  ```
  This will add the new parser to the list of metadata parsers.
  +The `@id` value is needed so Components.js knows which object to add the values to,
  +and the `@type` is needed so it can interpret the other fields (`handlers` in this case).
  Note that generally it is only advised to append to ParallelHandlers or key/value maps.
  In case the order is important this can not be guaranteed over separate files.
  