Update docuement

Author: TonyCTHsu

guides/queries/tracing.md

@@ -156,8 +156,7 @@ You may provide `options` as a `Hash` with the following values:
 
 | Key | Description | Default |
 | --- | ----------- | ------- |
-| `service` | Service name used for `graphql` instrumentation | `'ruby-graphql'` |
-| `tracer` | `Datadog::Tracer` used to perform instrumentation. Usually you don't need to set this. | `Datadog.tracer` |
+| `tracer` | Tracer used to perform instrumentation. Usually you don't need to set this. | `Datadog::Tracing` |
 
 For more details about Datadog's tracing API, check out the [Ruby documentation](https://github.com/DataDog/dd-trace-rb/blob/master/docs/GettingStarted.md) or the [APM documentation](https://docs.datadoghq.com/tracing/) for more product information.