Expand documentation around page load latency alert
Created by: caugustus-sourcegraph
Add some troubleshooting steps taken while investigating https://github.com/sourcegraph/customer/issues/572.
I didn't update the Grafana dashboards because the labels you choose to filter on will depend on the use case - for the above issue, filtering by job
revealed a problem, but in other situations filtering by route
or instance
may be more relevant.