Clarify how to add HTTP headers in the dashboard (#18558)

* Update http.mdx

* Update src/content/docs/logs/get-started/enable-destinations/http.mdx

---------

Co-authored-by: angelampcosta <[email protected]>

Author: Vortexmind

src/content/docs/logs/get-started/enable-destinations/http.mdx

@@ -19,6 +19,7 @@ Note that when using Logpush to HTTP endpoints, Cloudflare customers are expecte
 5. In **Select a destination**, choose **HTTP destination**.
 
 6. Enter the **HTTP endpoint** where you want to send the logs to, and select **Continue**.
+		- You can use `"header_*"` URL parameters to set request headers, for example, to pass an authentication token to your HTTP endpoint.
 
 7. Select the dataset to push to the storage service.