[v11.4.x] Alerting docs: clarify data source-managed rules for Prometheus (#98954)

Alerting docs: clarify data source-managed rules for Prometheus (#98378)

* Clarify DS managed rules support only the creation of Mimir and Loki rules

* additional copy changes

* Extend `Manage alerts via Alerting UI` description

* fix capital letter

* further details for `Manage alerts via Alerting UI`

(cherry picked from commit 7771768363)

Co-authored-by: Pepe Cano <825430+ppcano@users.noreply.github.com>

docs/sources/datasources/prometheus/configure-prometheus-data-source.md

@@ -31,6 +31,11 @@ refs:
       destination: /docs/grafana/<GRAFANA_VERSION>/panels-visualizations/configure-data-links/#value-variables
     - pattern: /docs/grafana-cloud/
       destination: /docs/grafana/<GRAFANA_VERSION>/panels-visualizations/configure-data-links/#value-variables
+  alerting-alert-rules:
+    - pattern: /docs/grafana/
+      destination: /docs/grafana/<GRAFANA_VERSION>/alerting/fundamentals/alert-rules/
+    - pattern: /docs/grafana-cloud/
+      destination: /docs/grafana-cloud/alerting-and-irm/alerting/fundamentals/alert-rules/
 ---
 
 # Configure Prometheus
@@ -115,7 +120,7 @@ Following are additional configuration options.
 
 ### Alerting
 
-- **Manage alerts via Alerting UI** - Toggle to enable `Alertmanager` integration for this data source.
+- **Manage alerts via Alerting UI** - Toggle to enable [data source-managed rules in Grafana Alerting](ref:alerting-alert-rules) for this data source. For `Mimir`, it enables managing data source-managed rules and alerts. For `Prometheus`, it only supports viewing existing rules and alerts, which are displayed as data source-managed.
 
 ### Interval behavior