docs(add): note about write endpoint usage only possible with custom datasources (#5784)

Author: nerda-codes

pages/cockpit/reference-content/cockpit-supported-endpoints.mdx

@@ -3,7 +3,7 @@ title: Cockpit supported API endpoints for data source management
 description: Discover how to manage your telemetry data sources using the Scaleway-supported Mimir, Loki, Tempo and Prometheus endpoints
 tags: observability cockpit endpoints mimir loki telemetry prometheus tempo datasource-management
 dates:
-  validation: 2025-07-17
+  validation: 2025-11-10
   posted: 2025-05-05
 ---
 import Requirements from '@macros/iam/requirements.mdx'
@@ -38,6 +38,10 @@ Refer to the [official Mimir documentation](https://grafana.com/docs/mimir/lates
 <Accordion>
   ## Mimir write endpoints
 
+    <Message type="note">
+     You can only use the write endpoints with custom data sources.
+    </Message>
+
     Method: `POST`.
 
     - Path: `/api/v1/push`
@@ -96,6 +100,10 @@ Refer to the [official Loki documentation](https://grafana.com/docs/loki/latest/
 <Accordion>
   ## Loki write endpoints
 
+    <Message type="note">
+     You can only use the write endpoints with custom data sources.
+    </Message>
+
     Method: `POST`.
 
     - Path: `/loki/api/v1/push`