Updating opentelemetry getting-started hyperlink

Per @abernix's [great suggestion](apollographql#1302 (review)), this PR does the following,

- Updates the link to "Getting Started" to the [most recent link provided in the OTel-JS Repo](https://github.com/open-telemetry/opentelemetry-js/blob/main/README.md?plain=1#L5)
  - This change in linking is documented in OTel-JS [commit apollographql#2493](open-telemetry/opentelemetry-js#2493)

docs/source/opentelemetry.mdx

@@ -208,7 +208,7 @@ Our example telemetry configuration assumes that Zipkin is running locally, and
 
 To prepare for production, we probably at least want to conditionally set the `url` option for the `ZipkinExporter` and replace our `SimpleSpanProcessor` with a `BatchSpanProcessor`.
 
-You can learn more about the settings available to these and other OpenTelemetry objects in the [getting started guide](https://github.com/open-telemetry/opentelemetry-js/tree/main/getting-started).
+You can learn more about the settings available to these and other OpenTelemetry objects in the [getting started guide](https://opentelemetry.io/docs/instrumentation/js/getting-started/).
 
 ## GraphQL-specific spans