Add useful Log Insights query to Nuxt avg response time runbook (#4089)

documentation/meta/monitoring/runbooks/nuxt_avg_response_time_above_threshold.md

@@ -20,12 +20,34 @@ previous version. Otherwise, check the following, in order:
 2. Check if dependencies like the API or Plausible analytics are constrained. If
    stable, move on.
 
+To gather more information check the [log group][log_group], use the "Logs
+Insights" view to query for requests that may be taking longer than expected
+with a CloudWatch query similar to the following which can give more hints about
+which routes are causing increased response times. Occasionally the `/api/event`
+endpoint will take longer to respond (due to upstream issues with Plausible),
+and these cases will increase our average response time while not actually
+affecting frontend performance for users. The following query shows the top 10
+routes where the request took longer than 0.5 seconds grouped by number of
+requests made to that route.
+
+```
+fields request, request_time, @timestamp, @message
+| filter request_time > 0.5
+| stats count(*) as request_count by request
+| sort request_count desc
+| limit 10
+```
+
 [traffic_runbook]:
   /meta/monitoring/traffic/runbooks/identifying-and-blocking-traffic-anomalies.md
+[log_group]:
+  https://us-east-1.console.aws.amazon.com/cloudwatch/home?region=us-east-1#logsV2:log-groups/log-group/$252Fecs$252Fproduction$252Ffrontend
 
 ## Historical false positives
 
-Nothing registered to date.
+- _2024-04-10, 22:00 UTC_: Requests to the `/api/event` endpoint were taking
+  longer than expected and impacted average response time, but not normal
+  frontend traffic response time.
 
 ## Related incident reports