Update beta-note-opentelemetry.mdx (#6554)

Author: smeubank

src/includes/beta-note-opentelemetry.mdx

@@ -4,6 +4,7 @@ OpenTelemetry Support is now generally availabile. If you have any questions or
 
 Currently, OpenTelemetry is supported on the following SDKs:
   - [NodeJS](https://docs.sentry.io/platforms/node/performance/instrumentation/opentelemetry/)
+  - [NextJS](https://docs.sentry.io/platforms/javascript/guides/nextjs/performance/instrumentation/opentelemetry/)
   - [Python](https://docs.sentry.io/platforms/python/performance/instrumentation/opentelemetry/)
   - [Ruby](https://docs.sentry.io/platforms/ruby/performance/instrumentation/opentelemetry/)
   - [Java](https://docs.sentry.io/platforms/java/performance/instrumentation/opentelemetry/)