Docs: Update prometheus.md (#30240)

* Update prometheus.md

* Update docs/sources/datasources/prometheus.md

Co-authored-by: Dan Cech <dcech@grafana.com>

* Update prometheus.md

Co-authored-by: Dan Cech <dcech@grafana.com>

docs/sources/datasources/prometheus.md

@@ -154,9 +154,18 @@ Grafana exposes metrics for Prometheus on the `/metrics` endpoint. We also bundl
 
 For detailed instructions, refer to [Internal Grafana metrics]({{< relref "../administration/metrics.md">}}).
 
+## Prometheus API
+
+The Prometheus data source works with other projects that implement the [Prometheus query API](https://prometheus.io/docs/prometheus/latest/querying/api/) including:
+
+- [Cortex](https://cortexmetrics.io/docs/)
+- [Thanos](https://thanos.io/v0.17/components/query.md/)
+
+For more information on how to query other Prometheus-compatible projects from Grafana, refer to the specific project documentation. 
+
 ## Provision the Prometheus data source
 
-You can configure data sources using config files with Grafana's provisioning system. Read more about how it works and all the settings you can set for data sources on the [provisioning docs page]({{< relref "../administration/provisioning/#datasources" >}})
+You can configure data sources using config files with Grafana's provisioning system. Read more about how it works and all the settings you can set for data sources on the [provisioning docs page]({{< relref "../administration/provisioning/#datasources" >}}).
 
 Here are some provisioning examples for this data source: