add workflow dispatch

Signed-off-by: nitishfy <justnitish06@gmail.com>

Author: nitishfy

.github/workflows/push-oci-manifet.yaml

@@ -1,11 +1,13 @@
 name: Push Rendered Manifests to OCI
 
 on:
-  push:
-    branches:
-      - main
-    paths:
-      - 'guestbook/**'
+  workflow_dispatch:
+  # Uncomment when trying to perform ci-based rendering for OCI (instead of kargo-based)
+  # push:
+  #   branches:
+  #     - main
+  #   paths:
+  #     - 'guestbook/**'
 
 permissions:
   contents: read