discovery.kubernetes docs: add example for node filtering (#5326)

Co-authored-by: Paschalis Tsilias <[email protected]>
Co-authored-by: Clayton Cornell <[email protected]>

docs/sources/flow/reference/components/discovery.kubernetes.md

@@ -458,3 +458,37 @@ Replace the following:
   - `PROMETHEUS_REMOTE_WRITE_URL`: The URL of the Prometheus remote_write-compatible server to send metrics to.
   - `USERNAME`: The username to use for authentication to the remote_write API.
   - `PASSWORD`: The password to use for authentication to the remote_write API.
+
+### Limit to only pods on the same node
+
+This example limits the search to pods on the same node as this Grafana Agent. This configuration could be useful if you are running the Agent as a DaemonSet:
+
+```river
+discovery.kubernetes "k8s_pods" {
+  role = "pod"
+  selectors {
+    role = "pod"
+    field = "spec.nodeName=" + constants.hostname
+  }
+}
+
+prometheus.scrape "demo" {
+  targets    = discovery.kubernetes.k8s_pods.targets
+  forward_to = [prometheus.remote_write.demo.receiver]
+}
+
+prometheus.remote_write "demo" {
+  endpoint {
+    url = PROMETHEUS_REMOTE_WRITE_URL
+
+    basic_auth {
+      username = USERNAME
+      password = PASSWORD
+    }
+  }
+}
+```
+Replace the following:
+  - `PROMETHEUS_REMOTE_WRITE_URL`: The URL of the Prometheus remote_write-compatible server to send metrics to.
+  - `USERNAME`: The username to use for authentication to the remote_write API.
+  - `PASSWORD`: The password to use for authentication to the remote_write API.