add alerting to 1.3.1 manifest (#1919)

Signed-off-by: Abhinav Gupta <[email protected]>

Author: abhinavGupta16

manifests/1.3.1/opensearch-dashboards-1.3.1.yml

@@ -39,3 +39,6 @@ components:
     repository: https://github.com/opensearch-project/observability.git
     working_directory: dashboards-observability
     ref: '1.3'
+  - name: alertingDashboards
+    repository: https://github.com/opensearch-project/alerting-dashboards-plugin.git
+    ref: '1.3'