content/en/docs/next/op-guide/monitoring.md: Add distributed tracing

content/en/docs/next/op-guide/monitoring.md

@@ -129,6 +129,23 @@ Sample dashboard:
 
 ![](../etcd-sample-grafana.png)
 
+## Distributed tracing
+
+In v3.5 etcd has added support for distributed tracing using [OpenTelemetry](https://github.com/open-telemetry).
+
+> Note: This feature is still experimental and can change at any time.
+
+To enable this experimental feature, pass the `--experimental-enable-distributed-tracing=true` to the etcd server. Setup and configure the distributed tracing by starting etcd server with the following flags:
+
+`--experimental-distributed-tracing-address` - (Optional) - "localhost:4317" - Address of the tracing collector.
+
+`--experimental-distributed-tracing-service-name` - (Optional) - "etcd" - Distributed tracing service name, must be same across all etcd instances.
+
+`--experimental-distributed-tracing-instance-id` - (Optional) - Instace ID, while optional it's strongly recommended to set, must be unique per etcd instance.
+
+Before enabling the distributed tracing, make sure to have the OpenTelemetry endpoint, if that address differs to the default one, override with the `--experimental-distributed-tracing-address` flag. Due to OpenTelemetry having different ways of running, refer to the [collector documentation](https://opentelemetry.io/docs/collector/getting-started/) to learn more.
+
+> Note: There is a resource overhead, as with any observability signal, according to our initial measurements that overhead could be between 2% - 4% CPU overhead.
 
 [grafana]: http://grafana.org/
 [prometheus]: https://prometheus.io/