docs: fix example in prometheus.exporter.agent (#5816)

(cherry picked from commit 26f4915)

Author: jkroepke

docs/sources/flow/reference/components/prometheus.exporter.agent.md

@@ -45,7 +45,7 @@ This example uses a [`prometheus.scrape` component][scrape] to collect metrics
 from `prometheus.exporter.agent`:
 
 ```river
-prometheus.exporter.agent "agent" {}
+prometheus.exporter.agent "example" {}
 
 // Configure a prometheus.scrape component to collect agent metrics.
 prometheus.scrape "demo" {
@@ -69,4 +69,4 @@ Replace the following:
   - `USERNAME`: The username to use for authentication to the remote_write API.
   - `PASSWORD`: The password to use for authentication to the remote_write API.
 
-[scrape]: {{< relref "./prometheus.scrape.md" >}}
+[scrape]: {{< relref "./prometheus.scrape.md" >}}