Update alerting.md

typo in API URL

docs/sources/http_api/alerting.md

@@ -202,7 +202,7 @@ This API can also be used to create, update and delete alert notifications.
 
 **Example Request**:
 
-    DELETE /api/alerts-notifications/1 HTTP/1.1
+    DELETE /api/alert-notifications/1 HTTP/1.1
     Accept: application/json
     Content-Type: application/json
     Authorization: Bearer eyJrIjoiT0tTcG1pUlY2RnVKZTFVaDFsNFZXdE9ZWmNrMkZYbk